Messages in this thread Patch in this message |  | | | Date | Wed, 12 Mar 2008 18:32:03 +0100 | | From | Martin Schwidefsky <> | | Subject | [patch 08/10] Add missing TLB flush to hugetlb_cow(). |
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From: Gerald Schaefer <geraldsc@de.ibm.com>
A cow break on a hugetlbfs page with page_count > 1 will set a new pte with set_huge_pte_at(), w/o any tlb flush operation. The old pte will remain in the tlb and subsequent write access to the page will result in a page fault loop, for as long as it may take until the tlb is flushed from somewhere else. This patch introduces an architecture-specific huge_ptep_clear_flush() function, which is called before the the set_huge_pte_at() in hugetlb_cow(). Cc: Andi Kleen <ak@suse.de> Cc: David S. Miller <davem@davemloft.net> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Signed-off-by: Gerald Schaefer <geraldsc@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> --- include/linux/hugetlb.h | 4 ++++ mm/hugetlb.c | 1 + 2 files changed, 5 insertions(+) Index: quilt-2.6/include/linux/hugetlb.h =================================================================== --- quilt-2.6.orig/include/linux/hugetlb.h +++ quilt-2.6/include/linux/hugetlb.h @@ -80,6 +80,10 @@ static inline int prepare_hugepage_range int prepare_hugepage_range(unsigned long addr, unsigned long len); #endif +#ifndef ARCH_HAS_HUGEPAGE_CLEAR_FLUSH +#define huge_ptep_clear_flush(vma, addr, ptep) do { } while (0) +#endif + #ifndef ARCH_HAS_SETCLEAR_HUGE_PTE #define set_huge_pte_at(mm, addr, ptep, pte) set_pte_at(mm, addr, ptep, pte) #define huge_ptep_get_and_clear(mm, addr, ptep) ptep_get_and_clear(mm, addr, ptep) Index: quilt-2.6/mm/hugetlb.c =================================================================== --- quilt-2.6.orig/mm/hugetlb.c +++ quilt-2.6/mm/hugetlb.c @@ -864,6 +864,7 @@ static int hugetlb_cow(struct mm_struct ptep = huge_pte_offset(mm, address & HPAGE_MASK); if (likely(pte_same(*ptep, pte))) { /* Break COW */ + huge_ptep_clear_flush(vma, address, ptep); set_huge_pte_at(mm, address, ptep, make_huge_pte(vma, new_page, 1)); /* Make the old page be freed below */ -- blue skies, Martin.
"Reality continues to ruin my life." - Calvin.
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