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mm/gup: Fix the lockless PMD access 

On architectures where the PTE/PMD is larger than the native word size
(i386-PAE for example), READ_ONCE() can do the wrong thing. Use
pmdp_get_lockless() just like we use ptep_get_lockless().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221022114424.906110403%40infradead.org
This commit is contained in:
Peter Zijlstra 2020-11-26 17:21:30 +01:00 committed by Dave Hansen
parent dab6e71742
commit 1180e732c9
2 changed files with 2 additions and 2 deletions
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2
kernel/events/core.c
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@ -7306,7 +7306,7 @@ static u64 perf_get_pgtable_size(struct mm_struct *mm, unsigned long addr)
return pud_leaf_size(pud);
pmdp = pmd_offset_lockless(pudp, pud, addr);
pmd = READ_ONCE(*pmdp);
pmd = pmdp_get_lockless(pmdp);
if (!pmd_present(pmd))
return 0;

2
mm/gup.c
View File

@ -2808,7 +2808,7 @@ static int gup_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr, unsigned lo
pmdp = pmd_offset_lockless(pudp, pud, addr);
do {
pmd_t pmd = READ_ONCE(*pmdp);
pmd_t pmd = pmdp_get_lockless(pmdp);
next = pmd_addr_end(addr, end);
if (!pmd_present(pmd))