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Mon, 31 Jul 2023 10:12:51 -0700 (PDT) Date: Mon, 31 Jul 2023 10:12:32 -0700 In-Reply-To: <20230731171233.1098105-1-surenb@google.com> Mime-Version: 1.0 References: <20230731171233.1098105-1-surenb@google.com> X-Mailer: git-send-email 2.41.0.487.g6d72f3e995-goog Message-ID: <20230731171233.1098105-7-surenb@google.com> Subject: [PATCH 6/6] mm: move vma locking out of vma_prepare From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org, jannh@google.com, willy@infradead.org, liam.howlett@oracle.com, david@redhat.com, peterx@redhat.com, ldufour@linux.ibm.com, vbabka@suse.cz, michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, hannes@cmpxchg.org, dave@stgolabs.net, hughd@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, Suren Baghdasaryan , Linus Torvalds X-Stat-Signature: of75sqhcm355eg7951fju1ah85ygwpfb X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 2BC03C0011 X-Rspam-User: X-HE-Tag: 1690823571-221327 X-HE-Meta: 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 u3kA/0vg 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: vma_prepare() is currently the central place where vmas are being locked before vma_complete() applies changes to them. While this is convenient, it also obscures vma locking and makes it hard to follow the locking rules. Move vma locking out of vma_prepare() and take vma locks explicitly at the locations where vmas are being modified. Suggested-by: Linus Torvalds Signed-off-by: Suren Baghdasaryan Reviewed-by: Liam R. Howlett --- mm/mmap.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 850a39dee075..e59d83cb1d7a 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -476,16 +476,6 @@ static inline void init_vma_prep(struct vma_prepare *vp, */ static inline void vma_prepare(struct vma_prepare *vp) { - vma_start_write(vp->vma); - if (vp->adj_next) - vma_start_write(vp->adj_next); - if (vp->insert) - vma_start_write(vp->insert); - if (vp->remove) - vma_start_write(vp->remove); - if (vp->remove2) - vma_start_write(vp->remove2); - if (vp->file) { uprobe_munmap(vp->vma, vp->vma->vm_start, vp->vma->vm_end); @@ -650,6 +640,7 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, bool remove_next = false; struct vma_prepare vp; + vma_start_write(vma); if (next && (vma != next) && (end == next->vm_end)) { int ret; @@ -657,6 +648,7 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, ret = dup_anon_vma(vma, next); if (ret) return ret; + vma_start_write(next); } init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL); @@ -708,6 +700,8 @@ int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma, if (vma_iter_prealloc(vmi)) return -ENOMEM; + vma_start_write(vma); + init_vma_prep(&vp, vma); vma_prepare(&vp); vma_adjust_trans_huge(vma, start, end, 0); @@ -946,10 +940,12 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, /* Can we merge both the predecessor and the successor? */ if (merge_prev && merge_next && is_mergeable_anon_vma(prev->anon_vma, next->anon_vma, NULL)) { + vma_start_write(next); remove = next; /* case 1 */ vma_end = next->vm_end; err = dup_anon_vma(prev, next); if (curr) { /* case 6 */ + vma_start_write(curr); remove = curr; remove2 = next; if (!next->anon_vma) @@ -958,6 +954,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, } else if (merge_prev) { /* case 2 */ if (curr) { err = dup_anon_vma(prev, curr); + vma_start_write(curr); if (end == curr->vm_end) { /* case 7 */ remove = curr; } else { /* case 5 */ @@ -969,6 +966,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, res = next; if (prev && addr < prev->vm_end) { /* case 4 */ vma_end = addr; + vma_start_write(next); adjust = next; adj_start = -(prev->vm_end - addr); err = dup_anon_vma(next, prev); @@ -983,6 +981,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, vma_pgoff = next->vm_pgoff - pglen; if (curr) { /* case 8 */ vma_pgoff = curr->vm_pgoff; + vma_start_write(curr); remove = curr; err = dup_anon_vma(next, curr); } @@ -996,6 +995,8 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, if (vma_iter_prealloc(vmi)) return NULL; + vma_start_write(vma); + init_multi_vma_prep(&vp, vma, adjust, remove, remove2); VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma && vp.anon_vma != adjust->anon_vma); @@ -2373,6 +2374,9 @@ int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, if (new->vm_ops && new->vm_ops->open) new->vm_ops->open(new); + vma_start_write(vma); + vma_start_write(new); + init_vma_prep(&vp, vma); vp.insert = new; vma_prepare(&vp); @@ -3078,6 +3082,8 @@ static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma, if (vma_iter_prealloc(vmi)) goto unacct_fail; + vma_start_write(vma); + init_vma_prep(&vp, vma); vma_prepare(&vp); vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);