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b=FGxENUExDJd15vnxkEJJOX9RFzx/yli0npWPMJNIfD+TXZS4mzFWYW4UssjxQKAgY LUG1BRfLBAofJn0SGbwyr82mb4BNIsIvViWofIDjZYpFoDYFAp3ylSj1DL4Wq3Lfvm jZSEk1Awn0SiCbl8jpkJA6VrVXxao31yIx4xDQ7ZwSt39p7uzjJGqN5Stv6XN+p1Wz cthl7ukNH7qWaWL4FgcSl98mNRadY7vNiWB9t95FrklFFvnJi9u6VJxy+BzuyjshEY Qd+sBN26cD200bgigwgEqeR3qGjnBTJO6Kq7sgujvelh5LAqaizjRMTlr/mG27bFPG QMxhq0ls4jdag== Date: Tue, 10 Nov 2026 14:49:40 +0100 From: Harry Yoo To: Alexei Starovoitov Cc: "Vlastimil Babka (SUSE)" , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Hao Li , Christoph Lameter , David Rientjes , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , kernel-team@meta.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, Sashiko Subject: Re: [PATCH for-next-fixes v2 4/5] mm/slab: fix a deadlock in memcg_alloc_abort_single() Message-ID: References: <20261103-kmalloc-nolock-fixes-v2-0-19167cfe4779@kernel.org> <20261103-kmalloc-nolock-fixes-v2-4-19167cfe4779@kernel.org> <6441429b-eff2-485b-acf3-26c3034910ae@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: yn47rbwsu8kfy3t3g78uhda8hsi7me4s X-Rspam-User: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 06E10A0006 X-HE-Tag: 1794318583-294558 X-HE-Meta: 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 iCjrs2H+ qkJUo6tUh/XVmM7HhgIqaTxPWfcFZwnUKrF4iEXF7Hmzb/iuXGfwXqjQarffAsWtY01F/pI2T0uXuYB5EUpTpX7O5thWfW/pgBS9ir38MPhODBuudhvJZ41pfpsuGRO1BRq6P7gL+Z7EPHyyL29cd5Fn0JK159LSW/nHYYxxQBOFa7LvrOHFGSGH8ua17dDvh9iDajYe44g+BUfaD+iw/BXIeNIPpcneL12OzQEKiwm16OWbn+c6o5Yd8Q0GfKbUad9HNfr0oHKJvvBLpekFHR1+bYErVQFyzwjX+5znlg6d5KtE3QUQlneYylGkVgZDQoaWK2b70eFQ9qikm+4AbCuuFSlJaZNIKU6UeoihILcFIwpykFUZEKMQIJhNvVYlVq7cIRU5TbV9+RsTotGULQAn4Cw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Wed, Nov 04, 2026 at 04:46:26PM +0000, Alexei Starovoitov wrote: > On Wed, Nov 04, 2026 at 07:35 AM Vlastimil Babka (SUSE) wrote: > >> I don't insist on kfree_nolock() there, > >> but can we try free_to_pcs() before defer_free() ? > >> Like: > >> > >> if (likely(allow_spin)) > >> __slab_free(s, slab, object, object, 1, _RET_IP_); > >> else if (!can_free_to_pcs(slab) || !free_to_pcs(s, object, false)) > >> defer_free(s, object); > > > > Why not try free_to_pcs with allow_spin as well then, and improve > > memcg_alloc_abort_single() for both contexts? > > yep. Even better. > The bulk side does that already. > Like: > > if (likely(can_free_to_pcs(slab)) && > likely(free_to_pcs(s, object, allow_spin))) > return; > > if (likely(allow_spin)) > __slab_free(s, slab, object, object, 1, _RET_IP_); > else > defer_free(s, object); > ? Will adjust in v3 (hopefully by end of this week!) Thanks. -- Cheers, Harry / Hyeonggon