diff options
| author | Dave Hansen <dave@sr71.net> | 2013-04-12 16:23:54 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-04-12 16:56:47 -0700 |
| commit | 1de14c3c5cbc9bb17e9dcc648cda51c0c85d54b9 (patch) | |
| tree | ab6010ad78195651c39a8ca3829ba1b95451762f /arch/x86/mm | |
| parent | bf81710c4b6e2df2cc047f7c8e1f342511904b74 (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 'arch/x86/mm')
| -rw-r--r-- | arch/x86/mm/pgtable.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 193350b51f90..17fda6a8b3c2 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -58,6 +58,13 @@ void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte) void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd) { paravirt_release_pmd(__pa(pmd) >> PAGE_SHIFT); + /* + * NOTE! For PAE, any changes to the top page-directory-pointer-table + * entries need a full cr3 reload to flush. + */ +#ifdef CONFIG_X86_PAE + tlb->need_flush_all = 1; +#endif tlb_remove_page(tlb, virt_to_page(pmd)); } |