summaryrefslogtreecommitdiffstats
path: root/mm/mmu_gather.c
AgeCommit message (Collapse)AuthorFilesLines
2019-06-13mm: mmu_gather: remove __tlb_reset_range() for force flushYang Shi1-5/+19
A few new fields were added to mmu_gather to make TLB flush smarter for huge page by telling what level of page table is changed. __tlb_reset_range() is used to reset all these page table state to unchanged, which is called by TLB flush for parallel mapping changes for the same range under non-exclusive lock (i.e. read mmap_sem). Before commit dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap"), the syscalls (e.g. MADV_DONTNEED, MADV_FREE) which may update PTEs in parallel don't remove page tables. But, the forementioned commit may do munmap() under read mmap_sem and free page tables. This may result in program hang on aarch64 reported by Jan Stancek. The problem could be reproduced by his test program with slightly modified below. ---8<--- static int map_size = 4096; static int num_iter = 500; static long threads_total; static void *distant_area; void *map_write_unmap(void *ptr) { int *fd = ptr; unsigned char *map_address; int i, j = 0; for (i = 0; i < num_iter; i++) { map_address = mmap(distant_area, (size_t) map_size, PROT_WRITE | PROT_READ, MAP_SHARED | MAP_ANONYMOUS, -1, 0); if (map_address == MAP_FAILED) { perror("mmap"); exit(1); } for (j = 0; j < map_size; j++) map_address[j] = 'b'; if (munmap(map_address, map_size) == -1) { perror("munmap"); exit(1); } } return NULL; } void *dummy(void *ptr) { return NULL; } int main(void) { pthread_t thid[2]; /* hint for mmap in map_write_unmap() */ distant_area = mmap(0, DISTANT_MMAP_SIZE, PROT_WRITE | PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); munmap(distant_area, (size_t)DISTANT_MMAP_SIZE); distant_area += DISTANT_MMAP_SIZE / 2; while (1) { pthread_create(&thid[0], NULL, map_write_unmap, NULL); pthread_create(&thid[1], NULL, dummy, NULL); pthread_join(thid[0], NULL); pthread_join(thid[1], NULL); } } ---8<--- The program may bring in parallel execution like below: t1 t2 munmap(map_address) downgrade_write(&mm->mmap_sem); unmap_region() tlb_gather_mmu() inc_tlb_flush_pending(tlb->mm); free_pgtables() tlb->freed_tables = 1 tlb->cleared_pmds = 1 pthread_exit() madvise(thread_stack, 8M, MADV_DONTNEED) zap_page_range() tlb_gather_mmu() inc_tlb_flush_pending(tlb->mm); tlb_finish_mmu() if (mm_tlb_flush_nested(tlb->mm)) __tlb_reset_range() __tlb_reset_range() would reset freed_tables and cleared_* bits, but this may cause inconsistency for munmap() which do free page tables. Then it may result in some architectures, e.g. aarch64, may not flush TLB completely as expected to have stale TLB entries remained. Use fullmm flush since it yields much better performance on aarch64 and non-fullmm doesn't yields significant difference on x86. The original proposed fix came from Jan Stancek who mainly debugged this issue, I just wrapped up everything together. Jan's testing results: v5.2-rc2-24-gbec7550cca10 -------------------------- mean stddev real 37.382 2.780 user 1.420 0.078 sys 54.658 1.855 v5.2-rc2-24-gbec7550cca10 + "mm: mmu_gather: remove __tlb_reset_range() for force flush" ---------------------------------------------------------------------------------------_ mean stddev real 37.119 2.105 user 1.548 0.087 sys 55.698 1.357 [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1558322252-113575-1-git-send-email-yang.shi@linux.alibaba.com Fixes: dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap") Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Jan Stancek <jstancek@redhat.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Suggested-by: Will Deacon <will.deacon@arm.com> Tested-by: Will Deacon <will.deacon@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <npiggin@gmail.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> [4.20+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-04-03asm-generic/tlb: Remove tlb_table_flush()Peter Zijlstra1-17/+17
There are no external users of this API (nor should there be); remove it. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-03asm-generic/tlb: Remove tlb_flush_mmu_free()Peter Zijlstra1-1/+1
As the comment notes; it is a potentially dangerous operation. Just use tlb_flush_mmu(), that will skip the (double) TLB invalidate if it really isn't needed anyway. No change in behavior intended. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-03asm-generic/tlb: Remove CONFIG_HAVE_GENERIC_MMU_GATHERPeter Zijlstra1-4/+0
Since all architectures are now using it, it is redundant. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-03asm-generic/tlb: Remove arch_tlb*_mmu()Peter Zijlstra1-51/+42
Now that all architectures are converted to the generic code, remove the arch hooks. No change in behavior intended. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-03asm-generic/tlb: Introduce CONFIG_HAVE_MMU_GATHER_NO_GATHER=yMartin Schwidefsky1-47/+60
Add the Kconfig option HAVE_MMU_GATHER_NO_GATHER to the generic mmu_gather code. If the option is set the mmu_gather will not track individual pages for delayed page free anymore. A platform that enables the option needs to provide its own implementation of the __tlb_remove_page_size() function to free pages. No change in behavior intended. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: aneesh.kumar@linux.vnet.ibm.com Cc: heiko.carstens@de.ibm.com Cc: linux@armlinux.org.uk Cc: npiggin@gmail.com Link: http://lkml.kernel.org/r/20180918125151.31744-2-schwidefsky@de.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-03asm-generic/tlb, arch: Invert CONFIG_HAVE_RCU_TABLE_INVALIDATEPeter Zijlstra1-1/+1
Make issuing a TLB invalidate for page-table pages the normal case. The reason is twofold: - too many invalidates is safer than too few, - most architectures use the linux page-tables natively and would thus require this. Make it an opt-out, instead of an opt-in. No change in behavior intended. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-03asm-generic/tlb, arch: Provide CONFIG_HAVE_MMU_GATHER_PAGE_SIZEPeter Zijlstra1-0/+5
Move the mmu_gather::page_size things into the generic code instead of PowerPC specific bits. No change in behavior intended. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nick Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-11-27mm: Replace call_rcu_sched() with call_rcu()Paul E. McKenney1-1/+1
Now that call_rcu()'s callback is not invoked until after all preempt-disable regions of code have completed (in addition to explicitly marked RCU read-side critical sections), call_rcu() can be used in place of call_rcu_sched(). This commit therefore makes that change. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-09-07mm/memory: Move mmu_gather and TLB invalidation code into its own filePeter Zijlstra1-0/+261
In preparation for maintaining the mmu_gather code as its own entity, move the implementation out of memory.c and into its own file. Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Will Deacon <will.deacon@arm.com>