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Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1tDwUw-00000005rF4-1u0R; Thu, 21 Nov 2024 02:00:46 +0000 Date: Thu, 21 Nov 2024 02:00:46 +0000 From: Matthew Wilcox To: Shakeel Butt Cc: Suren Baghdasaryan , akpm@linux-foundation.org, liam.howlett@oracle.com, lorenzo.stoakes@oracle.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mjguzik@gmail.com, oliver.sang@intel.com, mgorman@techsingularity.net, david@redhat.com, peterx@redhat.com, oleg@redhat.com, dave@stgolabs.net, paulmck@kernel.org, brauner@kernel.org, dhowells@redhat.com, hdanton@sina.com, hughd@google.com, minchan@google.com, jannh@google.com, souravpanda@google.com, pasha.tatashin@soleen.com, corbet@lwn.net, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v4 0/5] move per-vma lock into vm_area_struct Message-ID: References: <20241120000826.335387-1-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: 4denpn43ste5tc5awd98z1p43sp1fcbp X-Rspam-User: X-Rspamd-Queue-Id: 6ACD74000C X-Rspamd-Server: rspam02 X-HE-Tag: 1732154402-650461 X-HE-Meta: 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 enktrKe2 kzH/OmNeiaEyDAN//b96NjiwpAvacDw77DO+LfBf+i7NX34DApTrIPzJ1yTBsyko+Kkdun5px/OFYzB8mSNsjI3NlkMGKsCKoNpHCDoXzwudZSujS85I2zea+M43XdlNwtE58gO5CCA0J5qZGbxfyeyA3SWShDmSEMHpNlLqDLhLFUoPdxvx/kV+phXz3ogDqnV23PRFzc8IEP/LsRf6bLp7drUJAa5PtYJF4gEvR6aDIfzcwFpjK6V2401LfZN10uP9XHqDLl+oFJsf6yuXW/33NAb0p0qfBw9u+3P6yDfF0Lzk= 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 Wed, Nov 20, 2024 at 02:10:44PM -0800, Shakeel Butt wrote: > If 'struct vm_area_struct' is prone to performance issues due to > cacheline misalignments then we should do something about the > __randomize_layout tag for it. I imagine we can identify the fields > which might be performance critical to be on same cacheline or different > cacheline due to false sharing then we can divide the fields into > different cacheline groups and fields can be __randomize_layout within > the group. WDYT? Pretty sure the people who think security is more important than performance are the only ones who randomize structs.