diff options
authorShaohua Li <shaohua.li@intel.com>2011-03-16 11:37:29 +0800
committerGreg Kroah-Hartman <gregkh@suse.de>2011-03-23 13:04:08 -0700
commitbf59a586cad3de1d4419312826d4b759a4da0921 (patch)
parentd1342fed517f89ad4c3d956d9e214d72c06bb7c1 (diff)
x86: Flush TLB if PGD entry is changed in i386 PAE mode
commit 4981d01eada5354d81c8929d5b2836829ba3df7b upstream. 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> LKML-Reference: <1300246649.2337.95.camel@sli10-conroe> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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 94b979d1b58..effff47a3c8 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);
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 0113d19c8aa..8573b83a63d 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 */