path: root/mm
diff options
authorDave Hansen <dave@sr71.net>2013-04-12 16:23:54 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-04-12 16:56:47 -0700
commit1de14c3c5cbc9bb17e9dcc648cda51c0c85d54b9 (patch)
treeab6010ad78195651c39a8ca3829ba1b95451762f /mm
parentbf81710c4b6e2df2cc047f7c8e1f342511904b74 (diff)
x86-32: Fix possible incomplete TLB invalidate with PAE pagetables
This patch attempts to fix: https://bugzilla.kernel.org/show_bug.cgi?id=56461 The symptom is a crash and messages like this: chrome: Corrupted page table at address 34a03000 *pdpt = 0000000000000000 *pde = 0000000000000000 Bad pagetable: 000f [#1] PREEMPT SMP Ingo guesses this got introduced by commit 611ae8e3f520 ("x86/tlb: enable tlb flush range support for x86") since that code started to free unused pagetables. On x86-32 PAE kernels, that new code has the potential to free an entire PMD page and will clear one of the four page-directory-pointer-table (aka pgd_t entries). The hardware aggressively "caches" these top-level entries and invlpg does not actually affect the CPU's copy. If we clear one we *HAVE* to do a full TLB flush, otherwise we might continue using a freed pmd page. (note, we do this properly on the population side in pud_populate()). This patch tracks whenever we clear one of these entries in the 'struct mmu_gather', and ensures that we follow up with a full tlb flush. BTW, I disassembled and checked that: if (tlb->fullmm == 0) and if (!tlb->fullmm && !tlb->need_flush_all) generate essentially the same code, so there should be zero impact there to the !PAE case. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Artem S Tashkinov <t.artem@mailcity.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 494526ae024..13cbc420fea 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -216,6 +216,7 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
tlb->mm = mm;
tlb->fullmm = fullmm;
+ tlb->need_flush_all = 0;
tlb->start = -1UL;
tlb->end = 0;
tlb->need_flush = 0;