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From: Hao Li To: "Vlastimil Babka (SUSE)" Cc: Harry Yoo , Suren Baghdasaryan , Shakeel Butt , Alexander Potapenko , Marco Elver , Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org Subject: Re: [PATCH v3 10/13] mm/slab: reduce slabobj_ext memory with allocation profiling disabled Message-ID: References: <20260727-b4-objext_split-v3-0-c29ef0f1f257@kernel.org> <20260727-b4-objext_split-v3-10-c29ef0f1f257@kernel.org> <11f5028a-3fdc-47b4-9712-559c065b87ba@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <11f5028a-3fdc-47b4-9712-559c065b87ba@kernel.org> X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 6A0F4180003 X-Stat-Signature: 63dokem5km1hk5dek1hig4bwh1hqph7n X-HE-Tag: 1785412796-880062 X-HE-Meta: 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 uA4YOOgY Vt1mgxfNlSNQU6xqpRjJdv/aqXlKj9E6kKU951GuyiPy1VCcOe+VdO0aqrS/nTzl0wcuqtWE9F9S9C4bi5Bm1poKWVQOwOxjdqQNcKe8rKfkW+6B/SH2g/akFky63sZgFnLqH4ARkmEip1lQAQa872on7tT2iHf6AqAa5fgHCLubp+IHwcWg48btRV06fhFht6SgEFXNtS7BuROi4WNABIxmUavzv54QZkJWqEHgqeU/nO6HSBm7pfD+Ldhbw26JUkezk6IdsZcjHbQpWIh6zcc4liXC5QVaeOB33hWv5wyvWOfwzZpjdhNnGphcyihi7y2KPI6QJXsJxO/YlNIanPUhhv7Q5T7p/Szg8l93mp2Az7JY= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jul 27, 2026 at 04:07:48PM +0200, Vlastimil Babka (SUSE) wrote: > Per sashiko [1], a fixed up version below. Couldn't trigger the issue > although seems to me it's real. Perhaps can happen only with SLUB_TINY > otherwise the sheaf can't have obj_exts allocated from objcg charge path. > > [1] https://sashiko.dev/#/patchset/20260727-b4-objext_split-v3-0-c29ef0f1f257%40kernel.org?part=10 > > ----8<---- > From 905c6500e597a8ecf123ad167698f0a0c1a764bd Mon Sep 17 00:00:00 2001 > From: "Vlastimil Babka (SUSE)" > Date: Wed, 8 Jul 2026 17:04:36 +0200 > Subject: [PATCH] mm/slab: reduce slabobj_ext memory with allocation profiling > disabled > > When memory allocation profiling is compiled in but permanently disabled > on boot with (implicit or explicit) "never" parameter, stop allocating > (thus wasting) memory for the codetag_ref parts of slabobj_ext metadata. > > Do this by using the new slab_obj_ext_has_codetag() helper in > cache_obj_ext_size(). > > Additionally add slab_obj_ext_has_codetag() checks in > mark_obj_codetag_empty() and handle_failed_objexts_alloc(). The > functions might get called with memory allocation profiling disabled, > when the obj_ext array is allocated for objcg pointers only. Setting > codetag refs as empty is unnecessary in that case, and with them not > allocated anymore would now result in memory corruption. > > Reviewed-by: Suren Baghdasaryan > Signed-off-by: Vlastimil Babka (SUSE) LGTM. Reviewed-by: Hao Li -- Thanks, Hao