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Mon, 09 Jan 2023 12:54:39 -0800 (PST) Date: Mon, 9 Jan 2023 12:53:18 -0800 In-Reply-To: <20230109205336.3665937-1-surenb@google.com> Mime-Version: 1.0 References: <20230109205336.3665937-1-surenb@google.com> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20230109205336.3665937-24-surenb@google.com> Subject: [PATCH 23/41] mm: write-lock VMAs before removing them from VMA tree From: Suren Baghdasaryan To: akpm@linux-foundation.org Content-Type: text/plain; charset="UTF-8" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: michel@lespinasse.org, joelaf@google.com, songliubraving@fb.com, mhocko@suse.com, leewalsh@google.com, david@redhat.com, peterz@infradead.org, bigeasy@linutronix.de, peterx@redhat.com, dhowells@redhat.com, linux-mm@kvack.org, edumazet@google.com, jglisse@google.com, punit.agrawal@bytedance.com, arjunroy@google.com, dave@stgolabs.net, minchan@google.com, x86@kernel.org, hughd@google.com, willy@infradead.org, gurua@google.com, laurent.dufour@fr.ibm.com, linux-arm-kernel@lists.infradead.org, rientjes@google.com, axelrasmussen@google.com, kernel-team@android.com, soheil@google.com, paulmck@kernel.org, jannh@google.com, liam.howlett@oracle.com, shakeelb@google.com, luto@kernel.org, gthelen@google.com, ldufour@linux.ibm.com, surenb@google.com, vbabka@suse.cz, posk@google.com, lstoakes@gmail.com, peterjung1337@gmail.com, linuxppc-dev@lists.ozlabs.org, kent.overstreet@linux.dev, hughlynch@google.com, linux-kernel@vger.kernel.org, hannes@cmpxchg.org, tatashin@google.com, mgorman@techsingu larity.net Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Write-locking VMAs before isolating them ensures that page fault handlers don't operate on isolated VMAs. Signed-off-by: Suren Baghdasaryan --- mm/mmap.c | 2 ++ mm/nommu.c | 5 +++++ 2 files changed, 7 insertions(+) diff --git a/mm/mmap.c b/mm/mmap.c index da1908730828..be289e0b693b 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -448,6 +448,7 @@ void vma_mas_store(struct vm_area_struct *vma, struct ma_state *mas) */ void vma_mas_remove(struct vm_area_struct *vma, struct ma_state *mas) { + vma_write_lock(vma); trace_vma_mas_szero(mas->tree, vma->vm_start, vma->vm_end - 1); mas->index = vma->vm_start; mas->last = vma->vm_end - 1; @@ -2300,6 +2301,7 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, static inline int munmap_sidetree(struct vm_area_struct *vma, struct ma_state *mas_detach) { + vma_write_lock(vma); mas_set_range(mas_detach, vma->vm_start, vma->vm_end - 1); if (mas_store_gfp(mas_detach, vma, GFP_KERNEL)) return -ENOMEM; diff --git a/mm/nommu.c b/mm/nommu.c index b3154357ced5..7ae91337ef14 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -552,6 +552,7 @@ void vma_mas_store(struct vm_area_struct *vma, struct ma_state *mas) void vma_mas_remove(struct vm_area_struct *vma, struct ma_state *mas) { + vma_write_lock(vma); mas->index = vma->vm_start; mas->last = vma->vm_end - 1; mas_store_prealloc(mas, NULL); @@ -1551,6 +1552,10 @@ void exit_mmap(struct mm_struct *mm) mmap_write_lock(mm); for_each_vma(vmi, vma) { cleanup_vma_from_mm(vma); + /* + * No need to lock VMA because this is the only mm user and no + * page fault handled can race with it. + */ delete_vma(mm, vma); cond_resched(); } -- 2.39.0