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AJvYcCW7W5S/vYhGY09zVe72ABa1P0WPMI00pwp+1igoXfIzxkRIjrcGdyYFgeRYZnsKjL41E8kI0vPAAA==@kvack.org X-Gm-Message-State: AOJu0YxZyzSvF6mfoscmhMfXOqkh428MwuuO3AkPRpofs1rmiRVgzB/D NC1RYd+862+gxHJ/wFN0iyysKla+TUuIP4BciAUdwPwToaf8k25CssyrSSma3WYm9d66hGkbDRe +uYqSBcEE2MYHmroLrLEqQJ9w6s1VcVwQgBpp X-Gm-Gg: ASbGncurCRZlpMNU4Rzt1o1BCzQ00IGc6NoBtzVVyLQQHYJ+rvZnM2o1vqPBcBe6TrC lDIKG9jPg1g37IAbe3w8KvtVzdOOcay8= X-Google-Smtp-Source: AGHT+IE3NFWMPB84awBTKVHQKpIkIzfpP6rj90b+t0wNWbJd2/ytMK3K3Pnfa7aAXQadq08IftnKIN2x22mbUHavO30= X-Received: by 2002:a05:622a:54:b0:465:18f3:79c8 with SMTP id d75a77b69052e-4658aadae39mr3213131cf.13.1732288020964; Fri, 22 Nov 2024 07:07:00 -0800 (PST) MIME-Version: 1.0 References: <20241120000826.335387-1-surenb@google.com> In-Reply-To: From: Suren Baghdasaryan Date: Fri, 22 Nov 2024 07:06:49 -0800 Message-ID: Subject: Re: [PATCH v4 0/5] move per-vma lock into vm_area_struct To: Lorenzo Stoakes Cc: Matthew Wilcox , Shakeel Butt , akpm@linux-foundation.org, liam.howlett@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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 339A2140010 X-Stat-Signature: hamkb7ooh7etrq7eexeckk4b43f1hgwc X-HE-Tag: 1732287980-599277 X-HE-Meta: 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 CpcNBaof sTskgIEHaQiJEv4IUmmhspBvRVatQ1Nax2c2gSkDWJKEcBPW6nwbSX5+ZQxnr6D+ENWgDKvmEesE5sRp1kjOS+1B/U3IMVDmaXn7I9Q88IWnybgxHWof7QnUQXWVNbH/5gV81HHPuLeDYZTez5jw1U8VEmgVExg4e14Tx5gKc6umZgcb3JG58JVwzn+CnZ7AhlW1s1H2S2aNaTX/GDe7sulNcChv7aMfQlRAt7/DfOQp7tCWI35EomupEKG8f/rgvhzS8ry1gU5itR9g= 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 Fri, Nov 22, 2024 at 3:57=E2=80=AFAM Lorenzo Stoakes wrote: > > On Thu, Nov 21, 2024 at 02:00:46AM +0000, Matthew Wilcox wrote: > > 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 differ= ent > > > cacheline due to false sharing then we can divide the fields into > > > different cacheline groups and fields can be __randomize_layout withi= n > > > the group. WDYT? > > > > Pretty sure the people who think security is more important than > > performance are the only ones who randomize structs. > > I agree that I don't think we need concern ourselves with users of this > setting for precisely this reason. > > I wouldn't want supporting this to cause difficulty for users who do not > enable this when those who do aren't really concerned about the perf issu= es > as Matthew says. Ack. Will keep it as is. Thanks!