diff options
| -rw-r--r-- | fs/userfaultfd.c | 10 | ||||
| -rw-r--r-- | include/linux/pgtable.h | 17 | ||||
| -rw-r--r-- | mm/gup.c | 6 | ||||
| -rw-r--r-- | mm/hmm.c | 2 | ||||
| -rw-r--r-- | mm/khugepaged.c | 5 | ||||
| -rw-r--r-- | mm/ksm.c | 3 | ||||
| -rw-r--r-- | mm/memory.c | 14 | ||||
| -rw-r--r-- | mm/mprotect.c | 5 | ||||
| -rw-r--r-- | mm/page_vma_mapped.c | 2 |
9 files changed, 7 insertions, 57 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 0fd96d6e39ce..f7a0817b1ec0 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -349,15 +349,7 @@ static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx, if (!pud_present(*pud)) goto out; pmd = pmd_offset(pud, address); - /* - * READ_ONCE must function as a barrier with narrower scope - * and it must be equivalent to: - * _pmd = *pmd; barrier(); - * - * This is to deal with the instability (as in - * pmd_trans_unstable) of the pmd. - */ - _pmd = READ_ONCE(*pmd); + _pmd = pmdp_get_lockless(pmd); if (pmd_none(_pmd)) goto out; diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index c5a51481bbb9..8ec27fe69dc8 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -1345,23 +1345,6 @@ static inline int pmd_none_or_trans_huge_or_clear_bad(pmd_t *pmd) { pmd_t pmdval = pmdp_get_lockless(pmd); /* - * The barrier will stabilize the pmdval in a register or on - * the stack so that it will stop changing under the code. - * - * When CONFIG_TRANSPARENT_HUGEPAGE=y on x86 32bit PAE, - * pmdp_get_lockless is allowed to return a not atomic pmdval - * (for example pointing to an hugepage that has never been - * mapped in the pmd). The below checks will only care about - * the low part of the pmd with 32bit PAE x86 anyway, with the - * exception of pmd_none(). So the important thing is that if - * the low part of the pmd is found null, the high part will - * be also null or the pmd_none() check below would be - * confused. - */ -#ifdef CONFIG_TRANSPARENT_HUGEPAGE - barrier(); -#endif - /* * !pmd_present() checks for pmd migration entries * * The complete check uses is_pmd_migration_entry() in linux/swapops.h @@ -654,11 +654,7 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, struct mm_struct *mm = vma->vm_mm; pmd = pmd_offset(pudp, address); - /* - * The READ_ONCE() will stabilize the pmdval in a register or - * on the stack so that it will stop changing under the code. - */ - pmdval = READ_ONCE(*pmd); + pmdval = pmdp_get_lockless(pmd); if (pmd_none(pmdval)) return no_page_table(vma, flags); if (!pmd_present(pmdval)) @@ -332,7 +332,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, pmd_t pmd; again: - pmd = READ_ONCE(*pmdp); + pmd = pmdp_get_lockless(pmdp); if (pmd_none(pmd)) return hmm_vma_walk_hole(start, end, -1, walk); diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 3649ba12a235..2d206e62d358 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -959,11 +959,6 @@ static int find_pmd_or_thp_or_none(struct mm_struct *mm, return SCAN_PMD_NULL; pmde = pmdp_get_lockless(*pmd); - -#ifdef CONFIG_TRANSPARENT_HUGEPAGE - /* See comments in pmd_none_or_trans_huge_or_clear_bad() */ - barrier(); -#endif if (pmd_none(pmde)) return SCAN_PMD_NONE; if (!pmd_present(pmde)) @@ -1194,8 +1194,7 @@ static int replace_page(struct vm_area_struct *vma, struct page *page, * without holding anon_vma lock for write. So when looking for a * genuine pmde (in which to find pte), test present and !THP together. */ - pmde = *pmd; - barrier(); + pmde = pmdp_get_lockless(pmd); if (!pmd_present(pmde) || pmd_trans_huge(pmde)) goto out; diff --git a/mm/memory.c b/mm/memory.c index 36082fd42df4..221b21623644 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4923,18 +4923,9 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf) * So now it's safe to run pte_offset_map(). */ vmf->pte = pte_offset_map(vmf->pmd, vmf->address); - vmf->orig_pte = *vmf->pte; + vmf->orig_pte = ptep_get_lockless(vmf->pte); vmf->flags |= FAULT_FLAG_ORIG_PTE_VALID; - /* - * some architectures can have larger ptes than wordsize, - * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and - * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic - * accesses. The code below just needs a consistent view - * for the ifs and we later double check anyway with the - * ptl lock held. So here a barrier will do. - */ - barrier(); if (pte_none(vmf->orig_pte)) { pte_unmap(vmf->pte); vmf->pte = NULL; @@ -5058,9 +5049,8 @@ retry_pud: if (!(ret & VM_FAULT_FALLBACK)) return ret; } else { - vmf.orig_pmd = *vmf.pmd; + vmf.orig_pmd = pmdp_get_lockless(vmf.pmd); - barrier(); if (unlikely(is_swap_pmd(vmf.orig_pmd))) { VM_BUG_ON(thp_migration_supported() && !is_pmd_migration_entry(vmf.orig_pmd)); diff --git a/mm/mprotect.c b/mm/mprotect.c index 92d3d3ca390a..c5a13c0f1017 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -309,11 +309,6 @@ static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd) { pmd_t pmdval = pmdp_get_lockless(pmd); - /* See pmd_none_or_trans_huge_or_clear_bad for info on barrier */ -#ifdef CONFIG_TRANSPARENT_HUGEPAGE - barrier(); -#endif - if (pmd_none(pmdval)) return 1; if (pmd_trans_huge(pmdval)) diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index 4e448cfbc6ef..64aff6718bdb 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -210,7 +210,7 @@ restart: * compiler and used as a stale value after we've observed a * subsequent update. */ - pmde = READ_ONCE(*pvmw->pmd); + pmde = pmdp_get_lockless(pvmw->pmd); if (pmd_trans_huge(pmde) || is_pmd_migration_entry(pmde) || (pmd_present(pmde) && pmd_devmap(pmde))) { |