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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2018-02-01 03:18:16 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-01 04:18:38 +0300
commitd52605d7cb306aaf86d0e6dede275dbf8a020072 (patch)
tree2763bc71c0ebeb57c4ea93d95c030623ceb62060 /mm/pgtable-generic.c
parent86fa949b050184ffc53688516a6a83ae5f98d08a (diff)
downloadlinux-d52605d7cb306aaf86d0e6dede275dbf8a020072.tar.xz
mm: do not lose dirty and accessed bits in pmdp_invalidate()
Vlastimil noted that pmdp_invalidate() is not atomic and we can lose dirty and access bits if CPU sets them after pmdp dereference, but before set_pmd_at(). The patch change pmdp_invalidate() to make the entry non-present atomically and return previous value of the entry. This value can be used to check if CPU set dirty/accessed bits under us. The race window is very small and I haven't seen any reports that can be attributed to the bug. For this reason, I don't think backporting to stable trees needed. Link: http://lkml.kernel.org/r/20171213105756.69879-11-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David Daney <david.daney@cavium.com> Cc: David Miller <davem@davemloft.net> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Nitin Gupta <nitin.m.gupta@oracle.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/pgtable-generic.c')
-rw-r--r--mm/pgtable-generic.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 1e4ee763c190..cf2af04b34b9 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -181,12 +181,12 @@ pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
#endif
#ifndef __HAVE_ARCH_PMDP_INVALIDATE
-void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
+pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp)
{
- pmd_t entry = *pmdp;
- set_pmd_at(vma->vm_mm, address, pmdp, pmd_mknotpresent(entry));
+ pmd_t old = pmdp_establish(vma, address, pmdp, pmd_mknotpresent(*pmdp));
flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+ return old;
}
#endif