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authorShaohua Li <shaohua.li@intel.com>2011-03-16 11:37:29 +0800
committerIngo Molnar <mingo@elte.hu>2011-03-18 11:44:01 +0100
commit4981d01eada5354d81c8929d5b2836829ba3df7b (patch)
tree3f1e39b63111e06e2c213c6a0b1c5176e81a4ff9
parente8e999cf3cc733482e390b02ff25a64cecdc0b64 (diff)
x86: Flush TLB if PGD entry is changed in i386 PAE mode
According to intel CPU manual, every time PGD entry is changed in i386 PAE mode, we need do a full TLB flush. Current code follows this and there is comment for this too in the code. But current code misses the multi-threaded case. A changed page table might be used by several CPUs, every such CPU should flush TLB. Usually this isn't a problem, because we prepopulate all PGD entries at process fork. But when the process does munmap and follows new mmap, this issue will be triggered. When it happens, some CPUs keep doing page faults: http://marc.info/?l=linux-kernel&m=129915020508238&w=2 Reported-by: Yasunori Goto<y-goto@jp.fujitsu.com> Tested-by: Yasunori Goto<y-goto@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Shaohua Li<shaohua.li@intel.com> Cc: Mallick Asit K <asit.k.mallick@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-mm <linux-mm@kvack.org> Cc: stable <stable@kernel.org> LKML-Reference: <1300246649.2337.95.camel@sli10-conroe> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--arch/x86/include/asm/pgtable-3level.h11
-rw-r--r--arch/x86/mm/pgtable.c3
2 files changed, 4 insertions, 10 deletions
diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
index 94b979d1b58d..effff47a3c82 100644
--- a/arch/x86/include/asm/pgtable-3level.h
+++ b/arch/x86/include/asm/pgtable-3level.h
@@ -69,8 +69,6 @@ static inline void native_pmd_clear(pmd_t *pmd)
static inline void pud_clear(pud_t *pudp)
{
- unsigned long pgd;
-
set_pud(pudp, __pud(0));
/*
@@ -79,13 +77,10 @@ static inline void pud_clear(pud_t *pudp)
* section 8.1: in PAE mode we explicitly have to flush the
* TLB via cr3 if the top-level pgd is changed...
*
- * Make sure the pud entry we're updating is within the
- * current pgd to avoid unnecessary TLB flushes.
+ * Currently all places where pud_clear() is called either have
+ * flush_tlb_mm() followed or don't need TLB flush (x86_64 code or
+ * pud_clear_bad()), so we don't need TLB flush here.
*/
- pgd = read_cr3();
- if (__pa(pudp) >= pgd && __pa(pudp) <
- (pgd + sizeof(pgd_t)*PTRS_PER_PGD))
- write_cr3(pgd);
}
#ifdef CONFIG_SMP
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 0113d19c8aa6..8573b83a63d0 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -168,8 +168,7 @@ void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd)
* section 8.1: in PAE mode we explicitly have to flush the
* TLB via cr3 if the top-level pgd is changed...
*/
- if (mm == current->active_mm)
- write_cr3(read_cr3());
+ flush_tlb_mm(mm);
}
#else /* !CONFIG_X86_PAE */