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Wed, 9 Jul 2025 10:03:45 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id lleuL4E+bmhaGAAAD6G6ig (envelope-from ); Wed, 09 Jul 2025 10:03:45 +0000 Message-ID: Date: Wed, 9 Jul 2025 12:03:45 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 7/8] fs/proc/task_mmu: read proc/pid/maps under per-vma lock Content-Language: en-US To: Suren Baghdasaryan , akpm@linux-foundation.org Cc: Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, david@redhat.com, peterx@redhat.com, jannh@google.com, hannes@cmpxchg.org, mhocko@kernel.org, paulmck@kernel.org, shuah@kernel.org, adobriyan@gmail.com, brauner@kernel.org, josef@toxicpanda.com, yebin10@huawei.com, linux@weissschuh.net, willy@infradead.org, osalvador@suse.de, andrii@kernel.org, ryan.roberts@arm.com, christophe.leroy@csgroup.eu, tjmercier@google.com, kaleshsingh@google.com, aha310510@gmail.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org References: <20250704060727.724817-1-surenb@google.com> <20250704060727.724817-8-surenb@google.com> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: C6C0D4000D X-Stat-Signature: ya34d6oo4fgfgkmkjnwt7qe5fidhwpfh X-HE-Tag: 1752055427-655297 X-HE-Meta: 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 J9oJr2Ba QheVbWjQ6QILSAYoPAbtzJKOxFBJI2j7Ibx9VTRzlagJ3GtnMtsvjYgaqUPF4DPcN0ERh6zZDyDIaUPcY1w1h2pE/VhcEOhiiRpacgMP57nqXLxpSxnzDHK9ZCOoy5NBWAuQ2RBx5iutpEChTmzY/LQLsrPbYaKxcrGrh4LWL8FLY0waaSNmxsNSz+en5ZFpxllV4IqxTsXIpoxYPOJ1rAAHuugWn3trPWFoy0/891Q6lsGTxgXW3GxU/VEyaOuvtSx/Ja3kiDQM+53GEjt1yGC1CED1CLn6CQArbxCMJUMX4RF61KQJijrhK9Ol08EAcjI75Hag7XPLfM+CGF7wF+xbK5VM0Bf3vC6qRPKB820cxZZDF5JFeVtPGuA== 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: List-Subscribe: List-Unsubscribe: On 7/4/25 08:07, Suren Baghdasaryan wrote: > --- a/mm/mmap_lock.c > +++ b/mm/mmap_lock.c > @@ -178,6 +178,94 @@ struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm, > count_vm_vma_lock_event(VMA_LOCK_ABORT); > return NULL; > } > + > +static struct vm_area_struct *lock_vma_under_mmap_lock(struct mm_struct *mm, > + struct vma_iterator *iter, > + unsigned long address) > +{ > + struct vm_area_struct *vma; > + int ret; > + > + ret = mmap_read_lock_killable(mm); > + if (ret) > + return ERR_PTR(ret); > + > + /* Lookup the vma at the last position again under mmap_read_lock */ > + vma_iter_init(iter, mm, address); > + vma = vma_next(iter); > + if (vma) > + vma_start_read_locked(vma); This can in theory return false (refcount overflow?) so it should be handled? > + > + mmap_read_unlock(mm); > + > + return vma; > +} > +