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Commit 64cc6ae0 authored by Andrea Arcangeli's avatar Andrea Arcangeli Committed by Linus Torvalds
Browse files

thp: bail out gup_fast on splitting pmd 



Force gup_fast to take the slow path and block if the pmd is splitting,
not only if it's none.

Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarMel Gorman <mel@csn.ul.ie>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent db3eb96f

arch/x86/mm/gup.c

+12 −1
Original line number Original line Diff line number Diff line
@@ -160,7 +160,18 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end, 
		pmd_t pmd = *pmdp;

		pmd_t pmd = *pmdp;





		next = pmd_addr_end(addr, end);

		next = pmd_addr_end(addr, end);

		if (pmd_none(pmd))

		/*

		 * The pmd_trans_splitting() check below explains why

		 * pmdp_splitting_flush has to flush the tlb, to stop

		 * this gup-fast code from running while we set the

		 * splitting bit in the pmd. Returning zero will take

		 * the slow path that will call wait_split_huge_page()

		 * if the pmd is still in splitting state. gup-fast

		 * can't because it has irq disabled and

		 * wait_split_huge_page() would never return as the

		 * tlb flush IPI wouldn't run.

		 */

		if (pmd_none(pmd) || pmd_trans_splitting(pmd))

			return 0;

			return 0;

		if (unlikely(pmd_large(pmd))) {

		if (unlikely(pmd_large(pmd))) {

			if (!gup_huge_pmd(pmd, addr, next, write, pages, nr))

			if (!gup_huge_pmd(pmd, addr, next, write, pages, nr))