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b=K07H6DgppmhjUzA8+0NvjY7yHQipr4m8oLVhiW3s0IC2W+EupQPm6gJKU+28EOLMo ytsqmp2pAFMMQpfHQ0Wyna6YlGcqSQ+dgAV6MDlvYvPjzU8kQRGTkrG1lhPTqfArqI dVD+B8MamidXEDMwqT0ERIrfhYFIA3eoMDoVWtHSeDxJdLPXAmIQaGdzoC62l1El2G i8wpqlu2RXRNlt9QGkmYS9Qy3Pwts3AoFGKUsZpbwSDXJbq5FkiNKN6I0KH7pIa1hV wVqttZUVmqYAZqekG+NuIEvcr42DI0fAfY0mUmxdDr1FE9td5gy6RJd+Bw2QL7Zkxc nK+eCnmHWp8qw== Date: Mon, 2 Nov 2026 15:15:26 +0000 From: Harry Yoo To: Puranjay Mohan Cc: linux-mm@kvack.org, Vlastimil Babka , Andrew Morton Subject: Re: [PATCH] mm/slab: Call call_rcu() directly from __kfree_rcu_sheaf() in any context Message-ID: References: <20261016155340.3304319-1-puranjay@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261016155340.3304319-1-puranjay@kernel.org> X-Stat-Signature: jxzirr114xijcsmucyuskxzn8148s3o5 X-Rspamd-Queue-Id: 228AE40013 X-Rspam-User: X-Rspamd-Server: rspam12 X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1793632528-802209 X-HE-Meta: U2FsdGVkX19Rs/B6d7sWhe48VrtC7J0ovYe+pDkC9XPxiWiqbDdMweT2LSNo69OaIVHLWkyT1oOx/CpeT2XclHxVXEcmrV5DYJhrs4aHGvnw0361FuAPbs9dbV8WE+JQNinzHApzA6OEZSQyOWe7IfhQoYvCEWsgo7vL/dq8g2ZmPE1yTcPVi9ix2BjG0jRIHxbiKwMDFQ55hWXDFpXa0WAaCWgziECnAPP1i0XkqVLSvNN7ljE/J46XpTItDWAGRMTX5E03CsUHRkgyHnUprKli75sQBGzQLrRzsOyruKtWBJhowt312YaSfDb7r3HmJQY2FABel4xEQZ+E7M9loRsHUhessABJWH/4raV+DANkhvkIJTojitmcLeLfPv2mbxFqJ4zqaPptzvuWgl1O1IqIX1K95ldF1wyuSZMiW4kls7WfopbKQcLoNr3WjXXiz45xadH8qBeDO6bwXWlGURggoOxIk006BDTZkZxBnMF8Z9pUe+uGHueuHAkH5fVoPJyoB4A61cg0FrBoW8/CZdiRafq1wI3431itxD7qVmdq+oQCvfiJfMoyZH/4bh9gEfdu6idcVS3O9zQnTna6dQOFmtOckDHzMcgNjun1CgyrzVYOcn0iWO6w4UqTBwH1osf8Mim8ZjkrbvIJYVD30bU95ss33m71F/v8p4w7Hi3C9R2UVdaqE+qXseKSUkSrhPDcrgCOxwaWUtOAExhM5yFl+rDXR4gv5jcIik2V/DyNOp7/GfPzV7x3lIBPLPiEr21ddK59y6AA8qD+rbHnAi8OObEyLAgqAN6EfhrfcteKUuoP8ctHDNKcDun0jcstDayGutQ1A9Vrps8ETRI9URsFCgZFWGQ8KV9Y65yG4/SqHwYafbVGVwwQvcCJSjGRiUXGStd/PF5mhm3DpXulbikm7m3KcNw6Mt2LWn2Gmfb951ZU+o5rm3Wt23OBJHpr5eg7QBvjAk2SlooaasQ C7ofaRX2 igVjPetJG7BLENbpdWQKmXAOG+JSlHNeq8CR24fl0OGr+1Z31N/wALsQAEScUTwhknNoBrqlnxliKZnvfEA/PKtyN2B6aC3Lq4N5S1gEVRRyAwKXk52lt9N0U6/zpPt3Auiv0oJRPqlMTyaRUZxQhxudsE7scdV0vKvmb0Y8bux0pTnE1rEydD3hV933223Zvssh9N7+hm+mHdlycTEJRY5PTlUOE9EpRIsu53RgzjdvTEFfEa1wOeAY/GIalXCe7zMkDzcAhwX07isT5cwwHAuTHr2hoUo6zF/FSNF+9rzDrfu3tGtyiPkyNIZAQDZASJwvquSkH8oIjb+txWG0cFZdUrtZDGXCe2K9xl/uAHW/XaNs= 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 Fri, Oct 16, 2026 at 08:53:39AM -0700, Puranjay Mohan wrote: > __kfree_rcu_sheaf() can run with allow_spin == false, e.g. from > kfree_rcu_nolock(), where it may interrupt call_rcu() itself on the same > CPU. call_rcu() was not reentrant, so commit 69abda97a09b2 ("mm/slab: > extend deferred free mechanism to handle rcu sheaves") added a fallback: > when !allow_spin and IRQs are disabled, the full rcu sheaf is put on a > per-CPU llist and submitted to call_rcu() later from irq_work. > > call_rcu() now handles this itself. When it is called with IRQs disabled > (from NMI, or re-entered from instrumentation), it stages the callback on > a per-CPU list and re-issues it from irq_work. Callers no longer need to > guard against that, so always call call_rcu() directly and remove the > rcu_sheaves llist and its irq_work handling. > > Signed-off-by: Puranjay Mohan > --- Looks good to me, Reviewed-by: Harry Yoo (Meta) Thanks Puranjay for cleaning this up. -- Cheers, Harry / Hyeonggon