From 16fd20aa98080c2fa666dc384036ec08c80af710 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Fri, 11 Jan 2019 19:06:44 +0000 Subject: kbuild: Disable LD_DEAD_CODE_DATA_ELIMINATION with ftrace & GCC <= 4.7 When building using GCC 4.7 or older, -ffunction-sections & the -pg flag used by ftrace are incompatible. This causes warnings or build failures (where -Werror applies) such as the following: arch/mips/generic/init.c: error: -ffunction-sections disabled; it makes profiling impossible This used to be taken into account by the ordering of calls to cc-option from within the top-level Makefile, which was introduced by commit 90ad4052e85c ("kbuild: avoid conflict between -ffunction-sections and -pg on gcc-4.7"). Unfortunately this was broken when the CONFIG_LD_DEAD_CODE_DATA_ELIMINATION cc-option check was moved to Kconfig in commit e85d1d65cd8a ("kbuild: test dead code/data elimination support in Kconfig"), because the flags used by this check no longer include -pg. Fix this by not allowing CONFIG_LD_DEAD_CODE_DATA_ELIMINATION to be enabled at the same time as ftrace/CONFIG_FUNCTION_TRACER when building using GCC 4.7 or older. Signed-off-by: Paul Burton Fixes: e85d1d65cd8a ("kbuild: test dead code/data elimination support in Kconfig") Reported-by: Geert Uytterhoeven Cc: Nicholas Piggin Cc: stable@vger.kernel.org # v4.19+ Signed-off-by: Masahiro Yamada --- init/Kconfig | 1 + 1 file changed, 1 insertion(+) (limited to 'init') diff --git a/init/Kconfig b/init/Kconfig index d47cb77a220e..513fa544a134 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1124,6 +1124,7 @@ config LD_DEAD_CODE_DATA_ELIMINATION bool "Dead code and data elimination (EXPERIMENTAL)" depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION depends on EXPERT + depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800) depends on $(cc-option,-ffunction-sections -fdata-sections) depends on $(ld-option,--gc-sections) help -- cgit v1.2.3 From 980768338488921b15c2f01d67f0324a48ef8625 Mon Sep 17 00:00:00 2001 From: Jonathan Neuschäfer Date: Fri, 1 Feb 2019 14:21:01 -0800 Subject: init/Kconfig: fix grammar by moving a closing parenthesis MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Link: http://lkml.kernel.org/r/20190129150813.15785-1-j.neuschaefer@gmx.net Signed-off-by: Jonathan Neuschäfer Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- init/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'init') diff --git a/init/Kconfig b/init/Kconfig index 513fa544a134..354146666d97 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -825,7 +825,7 @@ config CGROUP_PIDS PIDs controller is designed to stop this from happening. It should be noted that organisational operations (such as attaching - to a cgroup hierarchy will *not* be blocked by the PIDs controller), + to a cgroup hierarchy) will *not* be blocked by the PIDs controller, since the PIDs limit only affects a process's ability to fork, not to attach to a cgroup. -- cgit v1.2.3 From 7b2489d37e1e355228f7c55724f77580e1dec22a Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Fri, 1 Feb 2019 14:21:15 -0800 Subject: psi: clarify the Kconfig text for the default-disable option The current help text caused some confusion in online forums about whether or not to default-enable or default-disable psi in vendor kernels. This is because it doesn't communicate the reason for why we made this setting configurable in the first place: that the overhead is non-zero in an artificial scheduler stress test. Since this isn't representative of real workloads, and the effect was not measurable in scheduler-heavy real world applications such as the webservers and memcache installations at Facebook, it's fair to point out that this is a pretty cautious option to select. Link: http://lkml.kernel.org/r/20190129233617.16767-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner Reviewed-by: Andrew Morton Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- init/Kconfig | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'init') diff --git a/init/Kconfig b/init/Kconfig index 354146666d97..c9386a365eea 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -512,6 +512,17 @@ config PSI_DEFAULT_DISABLED per default but can be enabled through passing psi=1 on the kernel commandline during boot. + This feature adds some code to the task wakeup and sleep + paths of the scheduler. The overhead is too low to affect + common scheduling-intense workloads in practice (such as + webservers, memcache), but it does show up in artificial + scheduler stress tests, such as hackbench. + + If you are paranoid and not sure what the kernel will be + used for, say Y. + + Say N if unsure. + endmenu # "CPU/Task time and stats accounting" config CPU_ISOLATION -- cgit v1.2.3 From 2f1ee0913ce58efe7f18fbd518bd54c598559b89 Mon Sep 17 00:00:00 2001 From: Qian Cai Date: Tue, 12 Feb 2019 15:36:03 -0800 Subject: Revert "mm: use early_pfn_to_nid in page_ext_init" This reverts commit fe53ca54270a ("mm: use early_pfn_to_nid in page_ext_init"). When booting a system with "page_owner=on", start_kernel page_ext_init invoke_init_callbacks init_section_page_ext init_page_owner init_early_allocated_pages init_zones_in_node init_pages_in_zone lookup_page_ext page_to_nid The issue here is that page_to_nid() will not work since some page flags have no node information until later in page_alloc_init_late() due to DEFERRED_STRUCT_PAGE_INIT. Hence, it could trigger an out-of-bounds access with an invalid nid. UBSAN: Undefined behaviour in ./include/linux/mm.h:1104:50 index 7 is out of range for type 'zone [5]' Also, kernel will panic since flags were poisoned earlier with, CONFIG_DEBUG_VM_PGFLAGS=y CONFIG_NODE_NOT_IN_PAGE_FLAGS=n start_kernel setup_arch pagetable_init paging_init sparse_init sparse_init_nid memblock_alloc_try_nid_raw It did not handle it well in init_pages_in_zone() which ends up calling page_to_nid(). page:ffffea0004200000 is uninitialized and poisoned raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) page_owner info is not active (free page?) kernel BUG at include/linux/mm.h:990! RIP: 0010:init_page_owner+0x486/0x520 This means that assumptions behind commit fe53ca54270a ("mm: use early_pfn_to_nid in page_ext_init") are incomplete. Therefore, revert the commit for now. A proper way to move the page_owner initialization to sooner is to hook into memmap initialization. Link: http://lkml.kernel.org/r/20190115202812.75820-1-cai@lca.pw Signed-off-by: Qian Cai Acked-by: Michal Hocko Cc: Pasha Tatashin Cc: Mel Gorman Cc: Yang Shi Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- init/main.c | 3 ++- mm/page_ext.c | 4 +--- 2 files changed, 3 insertions(+), 4 deletions(-) (limited to 'init') diff --git a/init/main.c b/init/main.c index e2e80ca3165a..c86a1c8f19f4 100644 --- a/init/main.c +++ b/init/main.c @@ -695,7 +695,6 @@ asmlinkage __visible void __init start_kernel(void) initrd_start = 0; } #endif - page_ext_init(); kmemleak_init(); setup_per_cpu_pageset(); numa_policy_init(); @@ -1131,6 +1130,8 @@ static noinline void __init kernel_init_freeable(void) sched_init_smp(); page_alloc_init_late(); + /* Initialize page ext after all struct pages are initialized. */ + page_ext_init(); do_basic_setup(); diff --git a/mm/page_ext.c b/mm/page_ext.c index ae44f7adbe07..8c78b8d45117 100644 --- a/mm/page_ext.c +++ b/mm/page_ext.c @@ -398,10 +398,8 @@ void __init page_ext_init(void) * We know some arch can have a nodes layout such as * -------------pfn--------------> * N0 | N1 | N2 | N0 | N1 | N2|.... - * - * Take into account DEFERRED_STRUCT_PAGE_INIT. */ - if (early_pfn_to_nid(pfn) != nid) + if (pfn_to_nid(pfn) != nid) continue; if (init_section_page_ext(pfn, nid)) goto oom; -- cgit v1.2.3