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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qUDiC-00EvmZ-1j; Thu, 10 Aug 2023 22:00:56 +0000 Date: Thu, 10 Aug 2023 23:00:55 +0100 From: Matthew Wilcox To: David Hildenbrand Cc: Suren Baghdasaryan , akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@suse.com, josef@toxicpanda.com, jack@suse.cz, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, michel@lespinasse.org, liam.howlett@oracle.com, jglisse@google.com, vbabka@suse.cz, minchan@google.com, dave@stgolabs.net, punit.agrawal@bytedance.com, lstoakes@gmail.com, hdanton@sina.com, apopple@nvidia.com, peterx@redhat.com, ying.huang@intel.com, yuzhao@google.com, dhowells@redhat.com, hughd@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, pasha.tatashin@soleen.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v7 0/6] Per-VMA lock support for swap and userfaults Message-ID: References: <0ab6524a-6917-efe2-de69-f07fb5cdd9d2@redhat.com> <01e20a4a-35dc-b342-081f-0edaf8780f51@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <01e20a4a-35dc-b342-081f-0edaf8780f51@redhat.com> X-Rspamd-Queue-Id: 6C1CA180022 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: zjxm5s1eo9uuecimoqs3wm1myz8ufbdu X-HE-Tag: 1691704929-922942 X-HE-Meta: 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 EJTbnWCS hyiIddv65faCxjBdB5fKAY9dd6KWxOEqiK2zHzJDcPNxuzU0EGqpJAWVWum0toYK5fn1wEzmrIFv0suZ9LS8NND+SkUXhtCbx1crcaxU3qsd9PeyE6E6wehBa1WrmKU+VwcmaaXIv8eF5CEc= 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 Thu, Aug 10, 2023 at 09:40:57AM +0200, David Hildenbrand wrote: > I won't lie: all of these locking checks are a bit hard to get and possibly > even harder to maintain. > > Maybe better mmap unlock sanity checks as spelled out above might help > improve part of the situation. > > > And maybe some comments regarding the placement might help as well ;) The placement was obvious; we can't call into drivers under the vma lock. Not until we've audited all of them. I haven't yet had the chance to figure out exactly what is being fixed with this patch ... give me a few minutes.