Commit 1180e732 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Dave Hansen
Browse files

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: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221022114424.906110403%40infradead.org
parent dab6e717

kernel/events/core.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

mm/gup.c

+1 −1
Original line number Diff line number Diff line
@@ -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))