From 997f0ecb11da15602a3d34e10f9ca8418db794d0 Mon Sep 17 00:00:00 2001 From: "Vishal Moola (Oracle)" Date: Wed, 21 Feb 2024 15:47:28 -0800 Subject: mm/memory: change vmf_anon_prepare() to be non-static Patch series "Handle hugetlb faults under the VMA lock", v2. It is generally safe to handle hugetlb faults under the VMA lock. The only time this is unsafe is when no anon_vma has been allocated to this vma yet, so we can use vmf_anon_prepare() instead of anon_vma_prepare() to bailout if necessary. This should only happen for the first hugetlb page in the vma. Additionally, this patchset begins to use struct vm_fault within hugetlb_fault(). This works towards cleaning up hugetlb code, and should significantly reduce the number of arguments passed to functions. The last patch in this series may cause ltp hugemmap10 to "fail". This is because vmf_anon_prepare() may bailout with no anon_vma under the VMA lock after allocating a folio for the hugepage. In free_huge_folio(), this folio is completely freed on bailout iff there is a surplus of hugetlb pages. This will remove a folio off the freelist and decrement the number of hugepages while ltp expects these counters to remain unchanged on failure. The rest of the ltp testcases pass. This patch (of 2): In order to handle hugetlb faults under the VMA lock, hugetlb can use vmf_anon_prepare() to ensure we can safely prepare an anon_vma. Change it to be a non-static function so it can be used within hugetlb as well. Link: https://lkml.kernel.org/r/20240221234732.187629-6-vishal.moola@gmail.com Link: https://lkml.kernel.org/r/20240221234732.187629-2-vishal.moola@gmail.com Signed-off-by: Vishal Moola (Oracle) Reviewed-by: Matthew Wilcox (Oracle) Cc: Muchun Song Signed-off-by: Andrew Morton --- mm/internal.h | 1 + mm/memory.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/internal.h b/mm/internal.h index 93e229112045..2b7efffbe4d7 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -103,6 +103,7 @@ static inline void wake_throttle_isolated(pg_data_t *pgdat) wake_up(wqh); } +vm_fault_t vmf_anon_prepare(struct vm_fault *vmf); vm_fault_t do_swap_page(struct vm_fault *vmf); void folio_rotate_reclaimable(struct folio *folio); bool __folio_end_writeback(struct folio *folio); diff --git a/mm/memory.c b/mm/memory.c index 642b4f2be523..1c45b6a42a1b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3280,7 +3280,7 @@ static inline vm_fault_t vmf_can_call_fault(const struct vm_fault *vmf) return VM_FAULT_RETRY; } -static vm_fault_t vmf_anon_prepare(struct vm_fault *vmf) +vm_fault_t vmf_anon_prepare(struct vm_fault *vmf) { struct vm_area_struct *vma = vmf->vma; -- cgit v1.2.3