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Mon, 09 Jan 2023 12:55:01 -0800 (PST) Date: Mon, 9 Jan 2023 12:53:27 -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: <20230109205336.3665937-33-surenb@google.com> Subject: [PATCH 32/41] mm: prevent userfaults to be handled under per-vma lock From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, paulmck@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, punit.agrawal@bytedance.com, lstoakes@gmail.com, peterjung1337@gmail.com, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@google.com, hughlynch@google.com, leewalsh@google.com, posk@google.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com, surenb@google.com X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 49FFA160006 X-Stat-Signature: sgk348qd4hk7hiumghpsqbiedjxx73we X-HE-Tag: 1673297702-173652 X-HE-Meta: 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 n2L5p3iS 7rrocRifvlSqPpmPX2Pgb945gcnIlp1kq0Cd2sYhmO0tSVSEp3Sa8kZMFkNqPNM7Uq6SxOrarHxbPSv7E+NMXNsPbxcnVbVgx+NJsagX2FQbkdYQpTOOygmYr/xqcGdsAK7sa3kUqX43Y3x/7g/ldwYbi/SKlTnxTR6eMkzACW0UwYUMTGC7wlVvodtDAO4tuUBBc1IXzP5pb/+cfmqTkciRuOCZr0faiCRVeSQKaDbkjSCd68s+gpULDneSmJQivp0H1yXesBfR6D/wGqmHaNn6k5A63Q7cI49M4oCU6GataiAt8GmiciGLwEbrWvYoq4wg9VzJ9uRNltg2cIDtHoTQx5sbyWw+t8/M7oJ3IHPAneSc= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000060, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Due to the possibility of handle_userfault dropping mmap_lock, avoid fault handling under VMA lock and retry holding mmap_lock. This can be handled more gracefully in the future. Signed-off-by: Suren Baghdasaryan Suggested-by: Peter Xu --- mm/memory.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/memory.c b/mm/memory.c index 20806bc8b4eb..12508f4d845a 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5273,6 +5273,13 @@ struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm, if (!vma->anon_vma) goto inval; + /* + * Due to the possibility of userfault handler dropping mmap_lock, avoid + * it for now and fall back to page fault handling under mmap_lock. + */ + if (userfaultfd_armed(vma)) + goto inval; + if (!vma_read_trylock(vma)) goto inval;