diff options
-rw-r--r-- | arch/x86/mm/gup.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c index 06f56fcf9a77..269aa53932e0 100644 --- a/arch/x86/mm/gup.c +++ b/arch/x86/mm/gup.c | |||
@@ -160,7 +160,18 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end, | |||
160 | pmd_t pmd = *pmdp; | 160 | pmd_t pmd = *pmdp; |
161 | 161 | ||
162 | next = pmd_addr_end(addr, end); | 162 | next = pmd_addr_end(addr, end); |
163 | if (pmd_none(pmd)) | 163 | /* |
164 | * The pmd_trans_splitting() check below explains why | ||
165 | * pmdp_splitting_flush has to flush the tlb, to stop | ||
166 | * this gup-fast code from running while we set the | ||
167 | * splitting bit in the pmd. Returning zero will take | ||
168 | * the slow path that will call wait_split_huge_page() | ||
169 | * if the pmd is still in splitting state. gup-fast | ||
170 | * can't because it has irq disabled and | ||
171 | * wait_split_huge_page() would never return as the | ||
172 | * tlb flush IPI wouldn't run. | ||
173 | */ | ||
174 | if (pmd_none(pmd) || pmd_trans_splitting(pmd)) | ||
164 | return 0; | 175 | return 0; |
165 | if (unlikely(pmd_large(pmd))) { | 176 | if (unlikely(pmd_large(pmd))) { |
166 | if (!gup_huge_pmd(pmd, addr, next, write, pages, nr)) | 177 | if (!gup_huge_pmd(pmd, addr, next, write, pages, nr)) |