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[2001:678:a5c:1202:4fb5:f16a:579c:6dcb]) by smtp.gmail.com with UTF8SMTPSA id 38308e7fff4ca-328085edc14sm32425801fa.107.2025.05.22.06.22.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 May 2025 06:22:21 -0700 (PDT) Date: Thu, 22 May 2025 15:22:21 +0200 From: Klara Modin To: JP Kobryn Cc: tj@kernel.org, shakeel.butt@linux.dev, yosryahmed@google.com, mkoutny@suse.com, hannes@cmpxchg.org, akpm@linux-foundation.org, linux-mm@kvack.org, cgroups@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH cgroup/for-6.16] cgroup: avoid per-cpu allocation of size zero rstat cpu locks Message-ID: References: <20250522013202.185523-1-inwardvessel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250522013202.185523-1-inwardvessel@gmail.com> X-Rspam-User: X-Rspamd-Queue-Id: 7D0FA20003 X-Rspamd-Server: rspam09 X-Stat-Signature: emjmyhod8aiquy396p1qdgafbozyrf76 X-HE-Tag: 1747920144-159519 X-HE-Meta: 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 VrFkbouo DHqSPHd2ih2sXjzH9bjbwGb6XknJLErsLA0YHd2johLjXYW8NU8PZB7E3yBdub4VIAxUj6A8H8UmgJtAnMZ0IYDPkpQMF5+LmHTqF891moQbtD/vyhsLtjziTxiZxHTkFGZNpE0uoYSGSTFtpF22nB2KFrQQv3E76FCQ7I1MjabAaJv42zWx41iR1NKVXBGjI915gWcpqEGXL7yd232KQxuD3EfJE6fxTi1E7VPpwqS6xz1dEoQusSLOOnmRVCnHGjA5cd+3ZvhVFjUt07daZrl65yVs/ieSzDVeKjtgIfctmp9pP2OdinmaJUR6UbUT7dj5mFX+X6vuigrQm5qVQ+OutRGqR63b2Uj4xG/sNL+gYtfbX9rSvYPnDDmXa8lCd4GTWSThD1aR70UPw6t0Uus5WlhVUGIJzVvZrjBuEW8haHK9yQWsfYDLVkQ== 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 2025-05-21 18:32:02 -0700, JP Kobryn wrote: > Subsystem rstat locks are dynamically allocated per-cpu. It was discovered > that a panic can occur during this allocation when the lock size is zero. > This is the case on non-smp systems, since arch_spinlock_t is defined as an > empty struct. Prevent this allocation when !CONFIG_SMP by adding a > pre-processor conditional around the affected block. > > Signed-off-by: JP Kobryn > Reported-by: Klara Modin > Fixes: 748922dcfabd ("cgroup: use subsystem-specific rstat locks to avoid contention") I can confirm this resolves the issue for me. Thanks, Tested-by: Klara Modin