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[209.85.167.42]) by smtp.gmail.com with ESMTPSA id e12-20020a2e984c000000b002b6cd89a3fcsm3258264ljj.118.2023.07.04.11.36.24 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 04 Jul 2023 11:36:24 -0700 (PDT) Received: by mail-lf1-f42.google.com with SMTP id 2adb3069b0e04-4fb8574a3a1so9192180e87.1 for ; Tue, 04 Jul 2023 11:36:24 -0700 (PDT) X-Received: by 2002:ac2:5b8b:0:b0:4f8:58f4:b96e with SMTP id o11-20020ac25b8b000000b004f858f4b96emr9284617lfn.37.1688495783799; Tue, 04 Jul 2023 11:36:23 -0700 (PDT) MIME-Version: 1.0 References: <20230704182442.1015301-1-Liam.Howlett@oracle.com> In-Reply-To: <20230704182442.1015301-1-Liam.Howlett@oracle.com> From: Linus Torvalds Date: Tue, 4 Jul 2023 11:36:06 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] mm/mmap: Clean up validate_mm() calls To: "Liam R. Howlett" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Oliver Sang Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 34C62A000E X-Stat-Signature: 58m1a3r9xshxkz9hxurrmqbfrmijgbqp X-Rspam-User: X-HE-Tag: 1688495786-630315 X-HE-Meta: U2FsdGVkX1/e0AkZ++FZ35jGTabH9E4XRevKsu3n8I1sgZRnXxE5F/WqxtOjFf1rn2+XN1z5fIZByB8jSNKy6FQ6Yj0oWJjwcCygTudiy22pda5NfIQwAdV7daBrDe9b6fflKpZXdPVIfLHRrKUybpL8bO4fOBb74U/KHV+XPi8PFKNYzNrK8c9JLNg/d12H234ZVYiBVbOiqKwJcjrRHP4/bbSYofwHbfORJNHGx9K4zPhtwQivI+b/96czIOCutY8Lwpc01kDmcRkYm1CXT3eCk9nbkaMLqdTvvfsw7js7OArC3fY7MdkbUwdsv2QgAZqSmDke18p4vWKg5//EHHVFXZRDBsfq+lHT8pnE5R1KgqSirTt7pVLF7qo/nexYQiIXMYzZG+REifS0OC+zuqf+6TtjOe4ajew0dZDqVln1qFyard2MafA1RChaSMYVSeiZJGkhD3UUES1Lb2LATDwAq7G5a4bR1OFSk2+aKerJVTzV8Opl29bu4ot+C0xm2R0nQs+bkChkP8G+VGloFEZ09qpLBk9IT8wlZ6FfI8XnXm2TBloYSdSn2QPSSI1WRBhucoOoPS5/kRlZAfwoAzg18ljD+GFgzqQreNQWi5gDnG4w9Ksi6SRXM4HzavD7iXnoUNq74PgNT+df+vkDefTm7udqYF8maP87I8YuthQt0pfqWvfEBmT8e67YoCD4EkuXmvDQobfgApDMbOw598Qbux//Bw5lf7RSTAW7HBcbX0HKjnAeycyZimdqSxucMA5g/3h92qizapOPLfNzdYYSXYM7J+bwbVS4KJ9yhztasbWf8E2XOeOt+gbBeuhwVye1bmUYfcYIJHhoCBOrza1mHkLfeFZeFInN/NmflX0UYiaVo2H3dmVS3UsMQb9pvomyKKhX2Py3JA9bh+lfiYwdAYLw1TP14EgX2HrUzH46RxUuG9PVcCeJpRK6zwq36XtVj+wF+5S3hKfcAVW USyVrca/ 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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: On Tue, 4 Jul 2023 at 11:25, Liam R. Howlett wrote: > > validate_mm() calls are too spread out and duplicated in numerous > locations. Also, now that the stack write is done under the write lock, > it is not necessary to validate the mm prior to write operations. So while I applied the fixes directly since I was doing all the write-locking stuff (and asked for the locking cleanup), I'm hoping these kinds of cleanups will now go back to normal and go through Andrew. I do have a question related to the write locking: now that we should always hold the mmap lock for writing when doing any modifications, can the "lock_is_held()" assertions be tightened? Right now it's "any locking", but for actual modification it should probably be using lockdep_is_held_type(mt->ma_external_lock, 1) but there's just one 'mt_lock_is_held()' function (presumably because the internal lock is always just a spinlock that doesn't have the reader/writer distinction). Linus