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2022-01-30memory-failure: fetch compound_head after pgmap_pfn_valid()Joao Martins1-0/+6
memory_failure_dev_pagemap() at the moment assumes base pages (e.g. dax_lock_page()). For devmap with compound pages fetch the compound_head in case a tail page memory failure is being handled. Currently this is a nop, but in the advent of compound pages in dev_pagemap it allows memory_failure_dev_pagemap() to keep working. Without this fix memory-failure handling (i.e. MCEs on pmem) with device-dax configured namespaces will regress (and crash). Link: https://lkml.kernel.org/r/20211202204422.26777-2-joao.m.martins@oracle.com Reported-by: Jane Chu <jane.chu@oracle.com> Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-15Merge branch 'akpm' (patches from Andrew)Linus Torvalds1-68/+119
Merge misc updates from Andrew Morton: "146 patches. Subsystems affected by this patch series: kthread, ia64, scripts, ntfs, squashfs, ocfs2, vfs, and mm (slab-generic, slab, kmemleak, dax, kasan, debug, pagecache, gup, shmem, frontswap, memremap, memcg, selftests, pagemap, dma, vmalloc, memory-failure, hugetlb, userfaultfd, vmscan, mempolicy, oom-kill, hugetlbfs, migration, thp, ksm, page-poison, percpu, rmap, zswap, zram, cleanups, hmm, and damon)" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (146 commits) mm/damon: hide kernel pointer from tracepoint event mm/damon/vaddr: hide kernel pointer from damon_va_three_regions() failure log mm/damon/vaddr: use pr_debug() for damon_va_three_regions() failure logging mm/damon/dbgfs: remove an unnecessary variable mm/damon: move the implementation of damon_insert_region to damon.h mm/damon: add access checking for hugetlb pages Docs/admin-guide/mm/damon/usage: update for schemes statistics mm/damon/dbgfs: support all DAMOS stats Docs/admin-guide/mm/damon/reclaim: document statistics parameters mm/damon/reclaim: provide reclamation statistics mm/damon/schemes: account how many times quota limit has exceeded mm/damon/schemes: account scheme actions that successfully applied mm/damon: remove a mistakenly added comment for a future feature Docs/admin-guide/mm/damon/usage: update for kdamond_pid and (mk|rm)_contexts Docs/admin-guide/mm/damon/usage: mention tracepoint at the beginning Docs/admin-guide/mm/damon/usage: remove redundant information Docs/admin-guide/mm/damon/usage: update for scheme quotas and watermarks mm/damon: convert macro functions to static inline functions mm/damon: modify damon_rand() macro to static inline function mm/damon: move damon_rand() definition into damon.h ...
2022-01-15mm: fix some comment errorsQuanfa Fu1-1/+1
Link: https://lkml.kernel.org/r/20211101040208.460810-1-fuqf0919@gmail.com Signed-off-by: Quanfa Fu <fuqf0919@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-15mm/hwpoison: fix unpoison_memory()Naoya Horiguchi1-19/+90
After recent soft-offline rework, error pages can be taken off from buddy allocator, but the existing unpoison_memory() does not properly undo the operation. Moreover, due to the recent change on __get_hwpoison_page(), get_page_unless_zero() is hardly called for hwpoisoned pages. So __get_hwpoison_page() highly likely returns -EBUSY (meaning to fail to grab page refcount) and unpoison just clears PG_hwpoison without releasing a refcount. That does not lead to a critical issue like kernel panic, but unpoisoned pages never get back to buddy (leaked permanently), which is not good. To (partially) fix this, we need to identify "taken off" pages from other types of hwpoisoned pages. We can't use refcount or page flags for this purpose, so a pseudo flag is defined by hacking ->private field. Someone might think that put_page() is enough to cancel taken-off pages, but the normal free path contains some operations not suitable for the current purpose, and can fire VM_BUG_ON(). Note that unpoison_memory() is now supposed to be cancel hwpoison events injected only by madvise() or /sys/devices/system/memory/{hard,soft}_offline_page, not by MCE injection, so please don't try to use unpoison when testing with MCE injection. [lkp@intel.com: report build failure for ARCH=i386] Link: https://lkml.kernel.org/r/20211115084006.3728254-4-naoya.horiguchi@linux.dev Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Ding Hui <dinghui@sangfor.com.cn> Cc: Tony Luck <tony.luck@intel.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-15mm/hwpoison: remove MF_MSG_BUDDY_2ND and MF_MSG_POISONED_HUGENaoya Horiguchi1-2/+0
These action_page_types are no longer used, so remove them. Link: https://lkml.kernel.org/r/20211115084006.3728254-3-naoya.horiguchi@linux.dev Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Acked-by: Yang Shi <shy828301@gmail.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: Ding Hui <dinghui@sangfor.com.cn> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: Tony Luck <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-15mm/hwpoison: mf_mutex for soft offline and unpoisonNaoya Horiguchi1-44/+18
Patch series "mm/hwpoison: fix unpoison_memory()", v4. The main purpose of this series is to sync unpoison code to recent changes around how hwpoison code takes page refcount. Unpoison should work or simply fail (without crash) if impossible. The recent works of keeping hwpoison pages in shmem pagecache introduce a new state of hwpoisoned pages, but unpoison for such pages is not supported yet with this series. It seems that soft-offline and unpoison can be used as general purpose page offline/online mechanism (not in the context of memory error). I think that we need some additional works to realize it because currently soft-offline and unpoison are assumed not to happen so frequently (print out too many messages for aggressive usecases). But anyway this could be another interesting next topic. v1: https://lore.kernel.org/linux-mm/20210614021212.223326-1-nao.horiguchi@gmail.com/ v2: https://lore.kernel.org/linux-mm/20211025230503.2650970-1-naoya.horiguchi@linux.dev/ v3: https://lore.kernel.org/linux-mm/20211105055058.3152564-1-naoya.horiguchi@linux.dev/ This patch (of 3): Originally mf_mutex is introduced to serialize multiple MCE events, but it is not that useful to allow unpoison to run in parallel with memory_failure() and soft offline. So apply mf_mutex to soft offline and unpoison. The memory failure handler and soft offline handler get simpler with this. Link: https://lkml.kernel.org/r/20211115084006.3728254-1-naoya.horiguchi@linux.dev Link: https://lkml.kernel.org/r/20211115084006.3728254-2-naoya.horiguchi@linux.dev Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: Ding Hui <dinghui@sangfor.com.cn> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: Tony Luck <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-15mm: shmem: don't truncate page if memory failure happensYang Shi1-3/+11
The current behavior of memory failure is to truncate the page cache regardless of dirty or clean. If the page is dirty the later access will get the obsolete data from disk without any notification to the users. This may cause silent data loss. It is even worse for shmem since shmem is in-memory filesystem, truncating page cache means discarding data blocks. The later read would return all zero. The right approach is to keep the corrupted page in page cache, any later access would return error for syscalls or SIGBUS for page fault, until the file is truncated, hole punched or removed. The regular storage backed filesystems would be more complicated so this patch is focused on shmem. This also unblock the support for soft offlining shmem THP. [akpm@linux-foundation.org: coding style fixes] [arnd@arndb.de: fix uninitialized variable use in me_pagecache_clean()] Link: https://lkml.kernel.org/r/20211022064748.4173718-1-arnd@kernel.org [Fix invalid pointer dereference in shmem_read_mapping_page_gfp() with a slight different implementation from what Ajay Garg <ajaygargnsit@gmail.com> and Muchun Song <songmuchun@bytedance.com> proposed and reworked the error handling of shmem_write_begin() suggested by Linus] Link: https://lore.kernel.org/linux-mm/20211111084617.6746-1-ajaygargnsit@gmail.com/ Link: https://lkml.kernel.org/r/20211020210755.23964-6-shy828301@gmail.com Link: https://lkml.kernel.org/r/20211116193247.21102-1-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: Ajay Garg <ajaygargnsit@gmail.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Andy Lavr <andy.lavr@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-10Merge tag 'x86_sgx_for_v5.17_rc1' of ↵Linus Torvalds1-6/+13
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 SGX updates from Borislav Petkov: - Add support for handling hw errors in SGX pages: poisoning, recovering from poison memory and error injection into SGX pages - A bunch of changes to the SGX selftests to simplify and allow of SGX features testing without the need of a whole SGX software stack - Add a sysfs attribute which is supposed to show the amount of SGX memory in a NUMA node, similar to what /proc/meminfo is to normal memory - The usual bunch of fixes and cleanups too * tag 'x86_sgx_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) x86/sgx: Fix NULL pointer dereference on non-SGX systems selftests/sgx: Fix corrupted cpuid macro invocation x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node x86/sgx: Fix minor documentation issues selftests/sgx: Add test for multiple TCS entry selftests/sgx: Enable multiple thread support selftests/sgx: Add page permission and exception test selftests/sgx: Rename test properties in preparation for more enclave tests selftests/sgx: Provide per-op parameter structs for the test enclave selftests/sgx: Add a new kselftest: Unclobbered_vdso_oversubscribed selftests/sgx: Move setup_test_encl() to each TEST_F() selftests/sgx: Encpsulate the test enclave creation selftests/sgx: Dump segments and /proc/self/maps only on failure selftests/sgx: Create a heap for the test enclave selftests/sgx: Make data measurement for an enclave segment optional selftests/sgx: Assign source for each segment selftests/sgx: Fix a benign linker warning x86/sgx: Add check for SGX pages to ghes_do_memory_failure() x86/sgx: Add hook to error injection address validation x86/sgx: Hook arch_memory_failure() into mainline code ...
2021-12-25mm/hwpoison: clear MF_COUNT_INCREASED before retrying get_any_page()Liu Shixin1-0/+1
Hulk Robot reported a panic in put_page_testzero() when testing madvise() with MADV_SOFT_OFFLINE. The BUG() is triggered when retrying get_any_page(). This is because we keep MF_COUNT_INCREASED flag in second try but the refcnt is not increased. page dumped because: VM_BUG_ON_PAGE(page_ref_count(page) == 0) ------------[ cut here ]------------ kernel BUG at include/linux/mm.h:737! invalid opcode: 0000 [#1] PREEMPT SMP CPU: 5 PID: 2135 Comm: sshd Tainted: G B 5.16.0-rc6-dirty #373 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 RIP: release_pages+0x53f/0x840 Call Trace: free_pages_and_swap_cache+0x64/0x80 tlb_flush_mmu+0x6f/0x220 unmap_page_range+0xe6c/0x12c0 unmap_single_vma+0x90/0x170 unmap_vmas+0xc4/0x180 exit_mmap+0xde/0x3a0 mmput+0xa3/0x250 do_exit+0x564/0x1470 do_group_exit+0x3b/0x100 __do_sys_exit_group+0x13/0x20 __x64_sys_exit_group+0x16/0x20 do_syscall_64+0x34/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae Modules linked in: ---[ end trace e99579b570fe0649 ]--- RIP: 0010:release_pages+0x53f/0x840 Link: https://lkml.kernel.org/r/20211221074908.3910286-1-liushixin2@huawei.com Fixes: b94e02822deb ("mm,hwpoison: try to narrow window race for free pages") Signed-off-by: Liu Shixin <liushixin2@huawei.com> Reported-by: Hulk Robot <hulkci@huawei.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-12-25mm, hwpoison: fix condition in free hugetlb page pathNaoya Horiguchi1-9/+4
When a memory error hits a tail page of a free hugepage, __page_handle_poison() is expected to be called to isolate the error in 4kB unit, but it's not called due to the outdated if-condition in memory_failure_hugetlb(). This loses the chance to isolate the error in the finer unit, so it's not optimal. Drop the condition. This "(p != head && TestSetPageHWPoison(head)" condition is based on the old semantics of PageHWPoison on hugepage (where PG_hwpoison flag was set on the subpage), so it's not necessray any more. By getting to set PG_hwpoison on head page for hugepages, concurrent error events on different subpages in a single hugepage can be prevented by TestSetPageHWPoison(head) at the beginning of memory_failure_hugetlb(). So dropping the condition should not reopen the race window originally mentioned in commit b985194c8c0a ("hwpoison, hugetlb: lock_page/unlock_page does not match for handling a free hugepage") [naoya.horiguchi@linux.dev: fix "HardwareCorrupted" counter] Link: https://lkml.kernel.org/r/20211220084851.GA1460264@u2004 Link: https://lkml.kernel.org/r/20211210110208.879740-1-naoya.horiguchi@linux.dev Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reported-by: Fei Luo <luofei@unicloud.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: <stable@vger.kernel.org> [5.14+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-15x86/sgx: Hook arch_memory_failure() into mainline codeTony Luck1-6/+13
Add a call inside memory_failure() to call the arch specific code to check if the address is an SGX EPC page and handle it. Note the SGX EPC pages do not have a "struct page" entry, so the hook goes in at the same point as the device mapping hook. Pull the call to acquire the mutex earlier so the SGX errors are also protected. Make set_mce_nospec() skip SGX pages when trying to adjust the 1:1 map. Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Tested-by: Reinette Chatre <reinette.chatre@intel.com> Link: https://lkml.kernel.org/r/20211026220050.697075-6-tony.luck@intel.com
2021-11-13Revert "mm: shmem: don't truncate page if memory failure happens"Linus Torvalds1-11/+3
This reverts commit b9d02f1bdd98f38e6e5ecacc9786a8f58f3f8b2c. The error handling of that patch was fundamentally broken, and it needs to be entirely re-done. For example, in shmem_write_begin() it would call shmem_getpage(), then ignore the error return from that, and look at the page pointer contents instead. And in shmem_read_mapping_page_gfp(), the patch tested PageHWPoison() on a page pointer that two lines earlier had potentially been set as an error pointer. These issues could be individually fixed, but when it has this many issues, I'm just reverting it instead of waiting for fixes. Link: https://lore.kernel.org/linux-mm/20211111084617.6746-1-ajaygargnsit@gmail.com/ Reported-by: Ajay Garg <ajaygargnsit@gmail.com> Reported-by: Jens Axboe <axboe@kernel.dk> Cc: Yang Shi <shy828301@gmail.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-06Merge branch 'akpm' (patches from Andrew)Linus Torvalds1-35/+76
Merge misc updates from Andrew Morton: "257 patches. Subsystems affected by this patch series: scripts, ocfs2, vfs, and mm (slab-generic, slab, slub, kconfig, dax, kasan, debug, pagecache, gup, swap, memcg, pagemap, mprotect, mremap, iomap, tracing, vmalloc, pagealloc, memory-failure, hugetlb, userfaultfd, vmscan, tools, memblock, oom-kill, hugetlbfs, migration, thp, readahead, nommu, ksm, vmstat, madvise, memory-hotplug, rmap, zsmalloc, highmem, zram, cleanups, kfence, and damon)" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (257 commits) mm/damon: remove return value from before_terminate callback mm/damon: fix a few spelling mistakes in comments and a pr_debug message mm/damon: simplify stop mechanism Docs/admin-guide/mm/pagemap: wordsmith page flags descriptions Docs/admin-guide/mm/damon/start: simplify the content Docs/admin-guide/mm/damon/start: fix a wrong link Docs/admin-guide/mm/damon/start: fix wrong example commands mm/damon/dbgfs: add adaptive_targets list check before enable monitor_on mm/damon: remove unnecessary variable initialization Documentation/admin-guide/mm/damon: add a document for DAMON_RECLAIM mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM) selftests/damon: support watermarks mm/damon/dbgfs: support watermarks mm/damon/schemes: activate schemes based on a watermarks mechanism tools/selftests/damon: update for regions prioritization of schemes mm/damon/dbgfs: support prioritization weights mm/damon/vaddr,paddr: support pageout prioritization mm/damon/schemes: prioritize regions within the quotas mm/damon/selftests: support schemes quotas mm/damon/dbgfs: support quotas of schemes ...
2021-11-06mm: hwpoison: handle non-anonymous THP correctlyYang Shi1-5/+2
Currently hwpoison doesn't handle non-anonymous THP, but since v4.8 THP support for tmpfs and read-only file cache has been added. They could be offlined by split THP, just like anonymous THP. Link: https://lkml.kernel.org/r/20211020210755.23964-7-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-06mm: shmem: don't truncate page if memory failure happensYang Shi1-3/+11
The current behavior of memory failure is to truncate the page cache regardless of dirty or clean. If the page is dirty the later access will get the obsolete data from disk without any notification to the users. This may cause silent data loss. It is even worse for shmem since shmem is in-memory filesystem, truncating page cache means discarding data blocks. The later read would return all zero. The right approach is to keep the corrupted page in page cache, any later access would return error for syscalls or SIGBUS for page fault, until the file is truncated, hole punched or removed. The regular storage backed filesystems would be more complicated so this patch is focused on shmem. This also unblock the support for soft offlining shmem THP. [arnd@arndb.de: fix uninitialized variable use in me_pagecache_clean()] Link: https://lkml.kernel.org/r/20211022064748.4173718-1-arnd@kernel.org Link: https://lkml.kernel.org/r/20211020210755.23964-6-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-06mm: hwpoison: refactor refcount check handlingYang Shi1-29/+64
Memory failure will report failure if the page still has extra pinned refcount other than from hwpoison after the handler is done. Actually the check is not necessary for all handlers, so move the check into specific handlers. This would make the following keeping shmem page in page cache patch easier. There may be expected extra pin for some cases, for example, when the page is dirty and in swapcache. Link: https://lkml.kernel.org/r/20211020210755.23964-5-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Suggested-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-06mm/memory_failure: constify static mm_walk_opsRikard Falkeborn1-1/+1
The only usage of hwp_walk_ops is to pass its address to walk_page_range() which takes a pointer to const mm_walk_ops as argument. Make it const to allow the compiler to put it in read-only memory. Link: https://lkml.kernel.org/r/20211014075042.17174-3-rikard.falkeborn@gmail.com Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-06mm: don't include <linux/dax.h> in <linux/mempolicy.h>Christoph Hellwig1-0/+1
Not required at all, and having this causes a huge kernel rebuild as soon as something in dax.h changes. Link: https://lkml.kernel.org/r/20210921082253.1859794-1-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-02Merge tag 'printk-for-5.16' of ↵Linus Torvalds1-4/+4
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk updates from Petr Mladek: - Extend %pGp print format to print hex value of the page flags - Use kvmalloc instead of kmalloc to allocate devkmsg buffers - Misc cleanup and warning fixes * tag 'printk-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: vsprintf: Update %pGp documentation about that it prints hex value lib/vsprintf.c: Amend static asserts for format specifier flags vsprintf: Make %pGp print the hex value test_printf: Append strings more efficiently test_printf: Remove custom appending of '|' test_printf: Remove separate page_flags variable test_printf: Make pft array const ia64: don't do IA64_CMPXCHG_DEBUG without CONFIG_PRINTK printk: use gnu_printf format attribute for printk_sprint() printk: avoid -Wsometimes-uninitialized warning printk: use kvmalloc instead of kmalloc for devkmsg_user
2021-11-01Merge tag 'folio-5.16' of git://git.infradead.org/users/willy/pagecacheLinus Torvalds1-1/+1
Pull memory folios from Matthew Wilcox: "Add memory folios, a new type to represent either order-0 pages or the head page of a compound page. This should be enough infrastructure to support filesystems converting from pages to folios. The point of all this churn is to allow filesystems and the page cache to manage memory in larger chunks than PAGE_SIZE. The original plan was to use compound pages like THP does, but I ran into problems with some functions expecting only a head page while others expect the precise page containing a particular byte. The folio type allows a function to declare that it's expecting only a head page. Almost incidentally, this allows us to remove various calls to VM_BUG_ON(PageTail(page)) and compound_head(). This converts just parts of the core MM and the page cache. For 5.17, we intend to convert various filesystems (XFS and AFS are ready; other filesystems may make it) and also convert more of the MM and page cache to folios. For 5.18, multi-page folios should be ready. The multi-page folios offer some improvement to some workloads. The 80% win is real, but appears to be an artificial benchmark (postgres startup, which isn't a serious workload). Real workloads (eg building the kernel, running postgres in a steady state, etc) seem to benefit between 0-10%. I haven't heard of any performance losses as a result of this series. Nobody has done any serious performance tuning; I imagine that tweaking the readahead algorithm could provide some more interesting wins. There are also other places where we could choose to create large folios and currently do not, such as writes that are larger than PAGE_SIZE. I'd like to thank all my reviewers who've offered review/ack tags: Christoph Hellwig, David Howells, Jan Kara, Jeff Layton, Johannes Weiner, Kirill A. Shutemov, Michal Hocko, Mike Rapoport, Vlastimil Babka, William Kucharski, Yu Zhao and Zi Yan. I'd also like to thank those who gave feedback I incorporated but haven't offered up review tags for this part of the series: Nick Piggin, Mel Gorman, Ming Lei, Darrick Wong, Ted Ts'o, John Hubbard, Hugh Dickins, and probably a few others who I forget" * tag 'folio-5.16' of git://git.infradead.org/users/willy/pagecache: (90 commits) mm/writeback: Add folio_write_one mm/filemap: Add FGP_STABLE mm/filemap: Add filemap_get_folio mm/filemap: Convert mapping_get_entry to return a folio mm/filemap: Add filemap_add_folio() mm/filemap: Add filemap_alloc_folio mm/page_alloc: Add folio allocation functions mm/lru: Add folio_add_lru() mm/lru: Convert __pagevec_lru_add_fn to take a folio mm: Add folio_evictable() mm/workingset: Convert workingset_refault() to take a folio mm/filemap: Add readahead_folio() mm/filemap: Add folio_mkwrite_check_truncate() mm/filemap: Add i_blocks_per_folio() mm/writeback: Add folio_redirty_for_writepage() mm/writeback: Add folio_account_redirty() mm/writeback: Add folio_clear_dirty_for_io() mm/writeback: Add folio_cancel_dirty() mm/writeback: Add folio_account_cleaned() mm/writeback: Add filemap_dirty_folio() ...
2021-10-28mm: filemap: check if THP has hwpoisoned subpage for PMD page faultYang Shi1-0/+14
When handling shmem page fault the THP with corrupted subpage could be PMD mapped if certain conditions are satisfied. But kernel is supposed to send SIGBUS when trying to map hwpoisoned page. There are two paths which may do PMD map: fault around and regular fault. Before commit f9ce0be71d1f ("mm: Cleanup faultaround and finish_fault() codepaths") the thing was even worse in fault around path. The THP could be PMD mapped as long as the VMA fits regardless what subpage is accessed and corrupted. After this commit as long as head page is not corrupted the THP could be PMD mapped. In the regular fault path the THP could be PMD mapped as long as the corrupted page is not accessed and the VMA fits. This loophole could be fixed by iterating every subpage to check if any of them is hwpoisoned or not, but it is somewhat costly in page fault path. So introduce a new page flag called HasHWPoisoned on the first tail page. It indicates the THP has hwpoisoned subpage(s). It is set if any subpage of THP is found hwpoisoned by memory failure and after the refcount is bumped successfully, then cleared when the THP is freed or split. The soft offline path doesn't need this since soft offline handler just marks a subpage hwpoisoned when the subpage is migrated successfully. But shmem THP didn't get split then migrated at all. Link: https://lkml.kernel.org/r/20211020210755.23964-3-shy828301@gmail.com Fixes: 800d8c63b2e9 ("shmem: add huge pages support") Signed-off-by: Yang Shi <shy828301@gmail.com> Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Suggested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-10-28mm: hwpoison: remove the unnecessary THP checkYang Shi1-14/+0
When handling THP hwpoison checked if the THP is in allocation or free stage since hwpoison may mistreat it as hugetlb page. After commit 415c64c1453a ("mm/memory-failure: split thp earlier in memory error handling") the problem has been fixed, so this check is no longer needed. Remove it. The side effect of the removal is hwpoison may report unsplit THP instead of unknown error for shmem THP. It seems not like a big deal. The following patch "mm: filemap: check if THP has hwpoisoned subpage for PMD page fault" depends on this, which fixes shmem THP with hwpoisoned subpage(s) are mapped PMD wrongly. So this patch needs to be backported to -stable as well. Link: https://lkml.kernel.org/r/20211020210755.23964-2-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Suggested-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-10-27vsprintf: Make %pGp print the hex valueMatthew Wilcox (Oracle)1-4/+4
All existing users of %pGp want the hex value as well as the decoded flag names. This looks awkward (passing the same parameter to printf twice), so move that functionality into the core. If we want, we can make that optional with flag arguments to %pGp in the future. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Yafang Shao <laoar.shao@gmail.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20211019142621.2810043-6-willy@infradead.org
2021-09-27mm/memcg: Convert mem_cgroup_uncharge() to take a folioMatthew Wilcox (Oracle)1-1/+1
Convert all the callers to call page_folio(). Most of them were already using a head page, but a few of them I can't prove were, so this may actually fix a bug. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
2021-09-24mm/memory_failure: fix the missing pte_unmap() callQi Zheng1-5/+5
The paired pte_unmap() call is missing before the dev_pagemap_mapping_shift() returns. So fix it. David says: "I guess this code never runs on 32bit / highmem, that's why we didn't notice so far". [akpm@linux-foundation.org: cleanup] Link: https://lkml.kernel.org/r/20210923122642.4999-1-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-24mm, hwpoison: add is_free_buddy_page() in HWPoisonHandlable()Naoya Horiguchi1-1/+1
Commit fcc00621d88b ("mm/hwpoison: retry with shake_page() for unhandlable pages") changed the return value of __get_hwpoison_page() to retry for transiently unhandlable cases. However, __get_hwpoison_page() currently fails to properly judge buddy pages as handlable, so hard/soft offline for buddy pages always fail as "unhandlable page". This is totally regrettable. So let's add is_free_buddy_page() in HWPoisonHandlable(), so that __get_hwpoison_page() returns different return values between buddy pages and unhandlable pages as intended. Link: https://lkml.kernel.org/r/20210909004131.163221-1-naoya.horiguchi@linux.dev Fixes: fcc00621d88b ("mm/hwpoison: retry with shake_page() for unhandlable pages") Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03Merge branch 'akpm' (patches from Andrew)Linus Torvalds1-27/+24
Merge misc updates from Andrew Morton: "173 patches. Subsystems affected by this series: ia64, ocfs2, block, and mm (debug, pagecache, gup, swap, shmem, memcg, selftests, pagemap, mremap, bootmem, sparsemem, vmalloc, kasan, pagealloc, memory-failure, hugetlb, userfaultfd, vmscan, compaction, mempolicy, memblock, oom-kill, migration, ksm, percpu, vmstat, and madvise)" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (173 commits) mm/madvise: add MADV_WILLNEED to process_madvise() mm/vmstat: remove unneeded return value mm/vmstat: simplify the array size calculation mm/vmstat: correct some wrong comments mm/percpu,c: remove obsolete comments of pcpu_chunk_populated() selftests: vm: add COW time test for KSM pages selftests: vm: add KSM merging time test mm: KSM: fix data type selftests: vm: add KSM merging across nodes test selftests: vm: add KSM zero page merging test selftests: vm: add KSM unmerge test selftests: vm: add KSM merge test mm/migrate: correct kernel-doc notation mm: wire up syscall process_mrelease mm: introduce process_mrelease system call memblock: make memblock_find_in_range method private mm/mempolicy.c: use in_task() in mempolicy_slab_node() mm/mempolicy: unify the create() func for bind/interleave/prefer-many policies mm/mempolicy: advertise new MPOL_PREFERRED_MANY mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY ...
2021-09-03mm/migrate: enable returning precise migrate_pages() success countYang Shi1-1/+1
Under normal circumstances, migrate_pages() returns the number of pages migrated. In error conditions, it returns an error code. When returning an error code, there is no way to know how many pages were migrated or not migrated. Make migrate_pages() return how many pages are demoted successfully for all cases, including when encountering errors. Page reclaim behavior will depend on this in subsequent patches. Link: https://lkml.kernel.org/r/20210721063926.3024591-3-ying.huang@intel.com Link: https://lkml.kernel.org/r/20210715055145.195411-4-ying.huang@intel.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Suggested-by: Oscar Salvador <osalvador@suse.de> [optional parameter] Reviewed-by: Yang Shi <shy828301@gmail.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Wei Xu <weixugc@google.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Keith Busch <kbusch@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03mm: fix panic caused by __page_handle_poison()Michael Wang1-2/+2
In commit 510d25c92ec4 ("mm/hwpoison: disable pcp for page_handle_poison()"), __page_handle_poison() was introduced, and if we mark: RET_A = dissolve_free_huge_page(); RET_B = take_page_off_buddy(); then __page_handle_poison was supposed to return TRUE When RET_A == 0 && RET_B == TRUE But since it failed to take care the case when RET_A is -EBUSY or -ENOMEM, and just return the ret as a bool which actually become TRUE, it break the original logic. The following result is a huge page in freelist but was referenced as poisoned, and lead into the final panic: kernel BUG at mm/internal.h:95! invalid opcode: 0000 [#1] SMP PTI skip... RIP: 0010:set_page_refcounted mm/internal.h:95 [inline] RIP: 0010:remove_hugetlb_page+0x23c/0x240 mm/hugetlb.c:1371 skip... Call Trace: remove_pool_huge_page+0xe4/0x110 mm/hugetlb.c:1892 return_unused_surplus_pages+0x8d/0x150 mm/hugetlb.c:2272 hugetlb_acct_memory.part.91+0x524/0x690 mm/hugetlb.c:4017 This patch replaces 'bool' with 'int' to handle RET_A correctly. Link: https://lkml.kernel.org/r/61782ac6-1e8a-4f6f-35e6-e94fce3b37f5@linux.alibaba.com Fixes: 510d25c92ec4 ("mm/hwpoison: disable pcp for page_handle_poison()") Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reported-by: Abaci <abaci@linux.alibaba.com> Cc: <stable@vger.kernel.org> [5.14+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03mm: hwpoison: dump page for unhandlable pageYang Shi1-3/+3
Currently just very simple message is shown for unhandlable page, e.g. non-LRU page, like: soft_offline: 0x1469f2: unknown non LRU page type 5ffff0000000000 () It is not very helpful for further debug, calling dump_page() could show more useful information. Calling dump_page() in get_any_page() in order to not duplicate the call in a couple of different places. It may be called with pcp disabled and holding memory hotplug lock, it should be not a big deal since hwpoison handler is not called very often. [shy828301@gmail.com: remove redundant pr_info per Noaya Horiguchi] Link: https://lkml.kernel.org/r/20210824020946.195257-3-shy828301@gmail.com Link: https://lkml.kernel.org/r/20210819054116.266126-3-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Suggested-by: Matthew Wilcox <willy@infradead.org> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: David Mackey <tdmackey@twitter.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03mm: hwpoison: don't drop slab caches for offlining non-LRU pageYang Shi1-10/+8
In the current implementation of soft offline, if non-LRU page is met, all the slab caches will be dropped to free the page then offline. But if the page is not slab page all the effort is wasted in vain. Even though it is a slab page, it is not guaranteed the page could be freed at all. However the side effect and cost is quite high. It does not only drop the slab caches, but also may drop a significant amount of page caches which are associated with inode caches. It could make the most workingset gone in order to just offline a page. And the offline is not guaranteed to succeed at all, actually I really doubt the success rate for real life workload. Furthermore the worse consequence is the system may be locked up and unusable since the page cache release may incur huge amount of works queued for memcg release. Actually we ran into such unpleasant case in our production environment. Firstly, the workqueue of memory_failure_work_func is locked up as below: BUG: workqueue lockup - pool cpus=1 node=0 flags=0x0 nice=0 stuck for 53s! Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=14/256 refcnt=15 in-flight: 409271:memory_failure_work_func pending: kfree_rcu_work, kfree_rcu_monitor, kfree_rcu_work, rht_deferred_worker, rht_deferred_worker, rht_deferred_worker, rht_deferred_worker, kfree_rcu_work, kfree_rcu_work, kfree_rcu_work, kfree_rcu_work, drain_local_stock, kfree_rcu_work workqueue mm_percpu_wq: flags=0x8 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=1/256 refcnt=2 pending: vmstat_update workqueue cgroup_destroy: flags=0x0 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=1/1 refcnt=12072 pending: css_release_work_fn There were over 12K css_release_work_fn queued, and this caused a few lockups due to the contention of worker pool lock with IRQ disabled, for example: NMI watchdog: Watchdog detected hard LOCKUP on cpu 1 Modules linked in: amd64_edac_mod edac_mce_amd crct10dif_pclmul crc32_pclmul ghash_clmulni_intel xt_DSCP iptable_mangle kvm_amd bpfilter vfat fat acpi_ipmi i2c_piix4 usb_storage ipmi_si k10temp i2c_core ipmi_devintf ipmi_msghandler acpi_cpufreq sch_fq_codel xfs libcrc32c crc32c_intel mlx5_core mlxfw nvme xhci_pci ptp nvme_core pps_core xhci_hcd CPU: 1 PID: 205500 Comm: kworker/1:0 Tainted: G L 5.10.32-t1.el7.twitter.x86_64 #1 Hardware name: TYAN F5AMT /z /S8026GM2NRE-CGN, BIOS V8.030 03/30/2021 Workqueue: events memory_failure_work_func RIP: 0010:queued_spin_lock_slowpath+0x41/0x1a0 Code: 41 f0 0f ba 2f 08 0f 92 c0 0f b6 c0 c1 e0 08 89 c2 8b 07 30 e4 09 d0 a9 00 01 ff ff 75 1b 85 c0 74 0e 8b 07 84 c0 74 08 f3 90 <8b> 07 84 c0 75 f8 b8 01 00 00 00 66 89 07 c3 f6 c4 01 75 04 c6 47 RSP: 0018:ffff9b2ac278f900 EFLAGS: 00000002 RAX: 0000000000480101 RBX: ffff8ce98ce71800 RCX: 0000000000000084 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8ce98ce6a140 RBP: 00000000000284c8 R08: ffffd7248dcb6808 R09: 0000000000000000 R10: 0000000000000003 R11: ffff9b2ac278f9b0 R12: 0000000000000001 R13: ffff8cb44dab9c00 R14: ffffffffbd1ce6a0 R15: ffff8cacaa37f068 FS: 0000000000000000(0000) GS:ffff8ce98ce40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fcf6e8cb000 CR3: 0000000a0c60a000 CR4: 0000000000350ee0 Call Trace: __queue_work+0xd6/0x3c0 queue_work_on+0x1c/0x30 uncharge_batch+0x10e/0x110 mem_cgroup_uncharge_list+0x6d/0x80 release_pages+0x37f/0x3f0 __pagevec_release+0x1c/0x50 __invalidate_mapping_pages+0x348/0x380 inode_lru_isolate+0x10a/0x160 __list_lru_walk_one+0x7b/0x170 list_lru_walk_one+0x4a/0x60 prune_icache_sb+0x37/0x50 super_cache_scan+0x123/0x1a0 do_shrink_slab+0x10c/0x2c0 shrink_slab+0x1f1/0x290 drop_slab_node+0x4d/0x70 soft_offline_page+0x1ac/0x5b0 memory_failure_work_func+0x6a/0x90 process_one_work+0x19e/0x340 worker_thread+0x30/0x360 kthread+0x116/0x130 The lockup made the machine is quite unusable. And it also made the most workingset gone, the reclaimabled slab caches were reduced from 12G to 300MB, the page caches were decreased from 17G to 4G. But the most disappointing thing is all the effort doesn't make the page offline, it just returns: soft_offline: 0x1469f2: unknown non LRU page type 5ffff0000000000 () It seems the aggressive behavior for non-LRU page didn't pay back, so it doesn't make too much sense to keep it considering the terrible side effect. Link: https://lkml.kernel.org/r/20210819054116.266126-1-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Reported-by: David Mackey <tdmackey@twitter.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03mm/hwpoison: fix some obsolete commentsMiaohe Lin1-3/+3
Since commit cb731d6c62bb ("vmscan: per memory cgroup slab shrinkers"), shrink_node_slabs is renamed to drop_slab_node. And doit argument is changed to forcekill since commit 6751ed65dc66 ("x86/mce: Fix siginfo_t->si_addr value for non-recoverable memory faults"). Link: https://lkml.kernel.org/r/20210814105131.48814-5-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03mm/hwpoison: change argument struct page **hpagep to *hpageMiaohe Lin1-4/+3
It's unnecessary to pass in a struct page **hpagep because it's never modified. Changing to use *hpage to simplify the code. Link: https://lkml.kernel.org/r/20210814105131.48814-4-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03mm/hwpoison: fix potential pte_unmap_unlock pte errorMiaohe Lin1-3/+4
If the first pte is equal to poisoned_pfn, i.e. check_hwpoisoned_entry() return 1, the wrong ptep - 1 would be passed to pte_unmap_unlock(). Link: https://lkml.kernel.org/r/20210814105131.48814-3-linmiaohe@huawei.com Fixes: ad9c59c24095 ("mm,hwpoison: send SIGBUS with error virutal address") Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03mm/hwpoison: remove unneeded variable unmap_successMiaohe Lin1-2/+1
Patch series "Cleanups and fixup for hwpoison" This series contains cleanups to remove unneeded variable, fix some obsolete comments and so on. Also we fix potential pte_unmap_unlock on wrong pte. More details can be found in the respective changelogs. This patch (of 4): unmap_success is used to indicate whether page is successfully unmapped but it's irrelated with ZONE_DEVICE page and unmap_success is always true here. Remove this unneeded one. Link: https://lkml.kernel.org/r/20210814105131.48814-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210814105131.48814-2-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-08-30Merge tag 'hole_punch_for_v5.15-rc1' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs Pull fs hole punching vs cache filling race fixes from Jan Kara: "Fix races leading to possible data corruption or stale data exposure in multiple filesystems when hole punching races with operations such as readahead. This is the series I was sending for the last merge window but with your objection fixed - now filemap_fault() has been modified to take invalidate_lock only when we need to create new page in the page cache and / or bring it uptodate" * tag 'hole_punch_for_v5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: filesystems/locking: fix Malformed table warning cifs: Fix race between hole punch and page fault ceph: Fix race between hole punch and page fault fuse: Convert to using invalidate_lock f2fs: Convert to using invalidate_lock zonefs: Convert to using invalidate_lock xfs: Convert double locking of MMAPLOCK to use VFS helpers xfs: Convert to use invalidate_lock xfs: Refactor xfs_isilocked() ext2: Convert to using invalidate_lock ext4: Convert to use mapping->invalidate_lock mm: Add functions to lock invalidate_lock for two mappings mm: Protect operations adding pages to page cache with invalidate_lock documentation: Sync file_operations members with reality mm: Fix comments mentioning i_mutex
2021-08-20mm/hwpoison: retry with shake_page() for unhandlable pagesNaoya Horiguchi1-3/+9
HWPoisonHandlable() sometimes returns false for typical user pages due to races with average memory events like transfers over LRU lists. This causes failures in hwpoison handling. There's retry code for such a case but does not work because the retry loop reaches the retry limit too quickly before the page settles down to handlable state. Let get_any_page() call shake_page() to fix it. [naoya.horiguchi@nec.com: get_any_page(): return -EIO when retry limit reached] Link: https://lkml.kernel.org/r/20210819001958.2365157-1-naoya.horiguchi@linux.dev Link: https://lkml.kernel.org/r/20210817053703.2267588-1-naoya.horiguchi@linux.dev Fixes: 25182f05ffed ("mm,hwpoison: fix race with hugetlb page allocation") Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reported-by: Tony Luck <tony.luck@intel.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: <stable@vger.kernel.org> [5.13+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-12mm: Fix comments mentioning i_mutexJan Kara1-1/+1
inode->i_mutex has been replaced with inode->i_rwsem long ago. Fix comments still mentioning i_mutex. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Jan Kara <jack@suse.cz>
2021-07-01mm: fix spelling mistakesZhen Lei1-1/+1
Fix some spelling mistakes in comments: each having differents usage ==> each has a different usage statments ==> statements adresses ==> addresses aggresive ==> aggressive datas ==> data posion ==> poison higer ==> higher precisly ==> precisely wont ==> won't We moves tha ==> We move the endianess ==> endianness Link: https://lkml.kernel.org/r/20210519065853.7723-2-thunder.leizhen@huawei.com Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Reviewed-by: Souptick Joarder <jrdr.linux@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-30mm: hwpoison_user_mappings() try_to_unmap() with TTU_SYNCHugh Dickins1-1/+1
TTU_SYNC prevents an unlikely race, when try_to_unmap() returns shortly before the page is accounted as unmapped. It is unlikely to coincide with hwpoisoning, but now that we have the flag, hwpoison_user_mappings() would do well to use it. Link: https://lkml.kernel.org/r/329c28ed-95df-9a2c-8893-b444d8a6d340@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Jan Kara <jack@suse.cz> Cc: Jue Wang <juew@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Wang Yugui <wangyugui@e16-tech.com> Cc: Yang Shi <shy828301@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-30mm: rmap: make try_to_unmap() void functionYang Shi1-8/+7
Currently try_to_unmap() return bool value by checking page_mapcount(), however this may return false positive since page_mapcount() doesn't check all subpages of compound page. The total_mapcount() could be used instead, but its cost is higher since it traverses all subpages. Actually the most callers of try_to_unmap() don't care about the return value at all. So just need check if page is still mapped by page_mapped() when necessary. And page_mapped() does bail out early when it finds mapped subpage. Link: https://lkml.kernel.org/r/bb27e3fe-6036-b637-5086-272befbfe3da@google.com Suggested-by: Hugh Dickins <hughd@google.com> Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Minchan Kim <minchan@kernel.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Jan Kara <jack@suse.cz> Cc: Jue Wang <juew@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Wang Yugui <wangyugui@e16-tech.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-30mm/hwpoison: disable pcp for page_handle_poison()Naoya Horiguchi1-3/+16
Recent changes by patch "mm/page_alloc: allow high-order pages to be stored on the per-cpu lists" makes kernels determine whether to use pcp by pcp_allowed_order(), which breaks soft-offline for hugetlb pages. Soft-offline dissolves a migration source page, then removes it from buddy free list, so it's assumed that any subpage of the soft-offlined hugepage are recognized as a buddy page just after returning from dissolve_free_huge_page(). pcp_allowed_order() returns true for hugetlb, so this assumption is no longer true. So disable pcp during dissolve_free_huge_page() and take_page_off_buddy() to prevent soft-offlined hugepages from linking to pcp lists. Soft-offline should not be common events so the impact on performance should be minimal. And I think that the optimization of Mel's patch could benefit to hugetlb so zone_pcp_disable() is called only in hwpoison context. Link: https://lkml.kernel.org/r/20210617092626.291006-1-nao.horiguchi@gmail.com Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-29mm,hwpoison: make get_hwpoison_page() call get_any_page()Naoya Horiguchi1-85/+109
__get_hwpoison_page() could fail to grab refcount by some race condition, so it's helpful if we can handle it by retrying. We already have retry logic, so make get_hwpoison_page() call get_any_page() when called from memory_failure(). As a result, get_hwpoison_page() can return negative values (i.e. error code), so some callers are also changed to handle error cases. soft_offline_page() does nothing for -EBUSY because that's enough and users in userspace can easily handle it. unpoison_memory() is also unchanged because it's broken and need thorough fixes (will be done later). Link: https://lkml.kernel.org/r/20210603233632.2964832-3-nao.horiguchi@gmail.com Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Tony Luck <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-29mm,hwpoison: send SIGBUS with error virutal addressNaoya Horiguchi1-1/+149
Now an action required MCE in already hwpoisoned address surely sends a SIGBUS to current process, but the SIGBUS doesn't convey error virtual address. That's not optimal for hwpoison-aware applications. To fix the issue, make memory_failure() call kill_accessing_process(), that does pagetable walk to find the error virtual address. It could find multiple virtual addresses for the same error page, and it seems hard to tell which virtual address is correct one. But that's rare and sending incorrect virtual address could be better than no address. So let's report the first found virtual address for now. [naoya.horiguchi@nec.com: fix walk_page_range() return] Link: https://lkml.kernel.org/r/20210603051055.GA244241@hori.linux.bs1.fc.nec.co.jp Link: https://lkml.kernel.org/r/20210521030156.2612074-4-nao.horiguchi@gmail.com Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Aili Yao <yaoaili@kingsoft.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Jue Wang <juew@google.com> Cc: Borislav Petkov <bp@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-24mm/hwpoison: do not lock page again when me_huge_page() successfully recoversNaoya Horiguchi1-14/+30
Currently me_huge_page() temporary unlocks page to perform some actions then locks it again later. My testcase (which calls hard-offline on some tail page in a hugetlb, then accesses the address of the hugetlb range) showed that page allocation code detects this page lock on buddy page and printed out "BUG: Bad page state" message. check_new_page_bad() does not consider a page with __PG_HWPOISON as bad page, so this flag works as kind of filter, but this filtering doesn't work in this case because the "bad page" is not the actual hwpoisoned page. So stop locking page again. Actions to be taken depend on the page type of the error, so page unlocking should be done in ->action() callbacks. So let's make it assumed and change all existing callbacks that way. Link: https://lkml.kernel.org/r/20210609072029.74645-1-nao.horiguchi@gmail.com Fixes: commit 78bb920344b8 ("mm: hwpoison: dissolve in-use hugepage in unrecoverable memory error") Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Tony Luck <tony.luck@intel.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-24mm,hwpoison: return -EHWPOISON to denote that the page has already been poisonedAili Yao1-1/+2
When memory_failure() is called with MF_ACTION_REQUIRED on the page that has already been hwpoisoned, memory_failure() could fail to send SIGBUS to the affected process, which results in infinite loop of MCEs. Currently memory_failure() returns 0 if it's called for already hwpoisoned page, then the caller, kill_me_maybe(), could return without sending SIGBUS to current process. An action required MCE is raised when the current process accesses to the broken memory, so no SIGBUS means that the current process continues to run and access to the error page again soon, so running into MCE loop. This issue can arise for example in the following scenarios: - Two or more threads access to the poisoned page concurrently. If local MCE is enabled, MCE handler independently handles the MCE events. So there's a race among MCE events, and the second or latter threads fall into the situation in question. - If there was a precedent memory error event and memory_failure() for the event failed to unmap the error page for some reason, the subsequent memory access to the error page triggers the MCE loop situation. To fix the issue, make memory_failure() return an error code when the error page has already been hwpoisoned. This allows memory error handler to control how it sends signals to userspace. And make sure that any process touching a hwpoisoned page should get a SIGBUS even in "already hwpoisoned" path of memory_failure() as is done in page fault path. Link: https://lkml.kernel.org/r/20210521030156.2612074-3-nao.horiguchi@gmail.com Signed-off-by: Aili Yao <yaoaili@kingsoft.com> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bp@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Jue Wang <juew@google.com> Cc: Tony Luck <tony.luck@intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-24mm/memory-failure: use a mutex to avoid memory_failure() racesTony Luck1-13/+23
Patch series "mm,hwpoison: fix sending SIGBUS for Action Required MCE", v5. I wrote this patchset to materialize what I think is the current allowable solution mentioned by the previous discussion [1]. I simply borrowed Tony's mutex patch and Aili's return code patch, then I queued another one to find error virtual address in the best effort manner. I know that this is not a perfect solution, but should work for some typical case. [1]: https://lore.kernel.org/linux-mm/20210331192540.2141052f@alex-virtual-machine/ This patch (of 2): There can be races when multiple CPUs consume poison from the same page. The first into memory_failure() atomically sets the HWPoison page flag and begins hunting for tasks that map this page. Eventually it invalidates those mappings and may send a SIGBUS to the affected tasks. But while all that work is going on, other CPUs see a "success" return code from memory_failure() and so they believe the error has been handled and continue executing. Fix by wrapping most of the internal parts of memory_failure() in a mutex. [akpm@linux-foundation.org: make mf_mutex local to memory_failure()] Link: https://lkml.kernel.org/r/20210521030156.2612074-1-nao.horiguchi@gmail.com Link: https://lkml.kernel.org/r/20210521030156.2612074-2-nao.horiguchi@gmail.com Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reviewed-by: Borislav Petkov <bp@suse.de> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Aili Yao <yaoaili@kingsoft.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: David Hildenbrand <david@redhat.com> Cc: Jue Wang <juew@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16mm/memory-failure: make sure wait for page writeback in memory_failureyangerkun1-1/+6
Our syzkaller trigger the "BUG_ON(!list_empty(&inode->i_wb_list))" in clear_inode: kernel BUG at fs/inode.c:519! Internal error: Oops - BUG: 0 [#1] SMP Modules linked in: Process syz-executor.0 (pid: 249, stack limit = 0x00000000a12409d7) CPU: 1 PID: 249 Comm: syz-executor.0 Not tainted 4.19.95 Hardware name: linux,dummy-virt (DT) pstate: 80000005 (Nzcv daif -PAN -UAO) pc : clear_inode+0x280/0x2a8 lr : clear_inode+0x280/0x2a8 Call trace: clear_inode+0x280/0x2a8 ext4_clear_inode+0x38/0xe8 ext4_free_inode+0x130/0xc68 ext4_evict_inode+0xb20/0xcb8 evict+0x1a8/0x3c0 iput+0x344/0x460 do_unlinkat+0x260/0x410 __arm64_sys_unlinkat+0x6c/0xc0 el0_svc_common+0xdc/0x3b0 el0_svc_handler+0xf8/0x160 el0_svc+0x10/0x218 Kernel panic - not syncing: Fatal exception A crash dump of this problem show that someone called __munlock_pagevec to clear page LRU without lock_page: do_mmap -> mmap_region -> do_munmap -> munlock_vma_pages_range -> __munlock_pagevec. As a result memory_failure will call identify_page_state without wait_on_page_writeback. And after truncate_error_page clear the mapping of this page. end_page_writeback won't call sb_clear_inode_writeback to clear inode->i_wb_list. That will trigger BUG_ON in clear_inode! Fix it by checking PageWriteback too to help determine should we skip wait_on_page_writeback. Link: https://lkml.kernel.org/r/20210604084705.3729204-1-yangerkun@huawei.com Fixes: 0bc1f8b0682c ("hwpoison: fix the handling path of the victimized page frame that belong to non-LRU") Signed-off-by: yangerkun <yangerkun@huawei.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Jan Kara <jack@suse.cz> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Oscar Salvador <osalvador@suse.de> Cc: Yu Kuai <yukuai3@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16mm,hwpoison: fix race with hugetlb page allocationNaoya Horiguchi1-2/+27
When hugetlb page fault (under overcommitting situation) and memory_failure() race, VM_BUG_ON_PAGE() is triggered by the following race: CPU0: CPU1: gather_surplus_pages() page = alloc_surplus_huge_page() memory_failure_hugetlb() get_hwpoison_page(page) __get_hwpoison_page(page) get_page_unless_zero(page) zero = put_page_testzero(page) VM_BUG_ON_PAGE(!zero, page) enqueue_huge_page(h, page) put_page(page) __get_hwpoison_page() only checks the page refcount before taking an additional one for memory error handling, which is not enough because there's a time window where compound pages have non-zero refcount during hugetlb page initialization. So make __get_hwpoison_page() check page status a bit more for hugetlb pages with get_hwpoison_huge_page(). Checking hugetlb-specific flags under hugetlb_lock makes sure that the hugetlb page is not transitive. It's notable that another new function, HWPoisonHandlable(), is helpful to prevent a race against other transitive page states (like a generic compound page just before PageHuge becomes true). Link: https://lkml.kernel.org/r/20210603233632.2964832-2-nao.horiguchi@gmail.com Fixes: ead07f6a867b ("mm/memory-failure: introduce get_hwpoison_page() for consistent refcount handling") Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reported-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Tony Luck <tony.luck@intel.com> Cc: <stable@vger.kernel.org> [5.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-07mm: fix typos in commentsIngo Molnar1-1/+1
Fix ~94 single-word typos in locking code comments, plus a few very obvious grammar mistakes. Link: https://lkml.kernel.org/r/20210322212624.GA1963421@gmail.com Link: https://lore.kernel.org/r/20210322205203.GB1959563@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Cc: Bhaskar Chowdhury <unixbhaskar@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>