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Sat, 15 Aug 2026 00:48:48 +0000 X-Migadu-Flow: FLOW_OUT Date: Fri, 14 Aug 2026 17:48:47 -0700 From: Shakeel Butt To: "Lorenzo Stoakes (ARM)" Cc: Andrew Morton , Michal Hocko , Johannes Weiner , Roman Gushchin , Muchun Song , David Hildenbrand , Kairui Song , Qi Zheng , Barry Song , Axel Rasmussen , Meta kernel team , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH for-7.4 0/9] memcg: remove the v1 soft limit Message-ID: References: <20260811203203.3456029-1-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Queue-Id: 19546C0004 X-Rspamd-Server: rspam07 X-Stat-Signature: srewre77ktyi7h9uq6gkjk8mtsr8rp3h X-HE-Tag: 1786754929-250855 X-HE-Meta: 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 PujM1yVi eqQVCtBL4anTIcQybxAJea5LE0+qcEZI2YNR+1COBtCttK5Y1ElcUaNBIx7UJJQPcWpiWXl+Eyc785AYuwL763QHFjzk8O5Ui31P8ccrD7qW7m4fb7XakA9i0FGiV1BfB3AIcYnq5A6Umi5ChTDyuKSZDUuxt3pCuCTiPYba+N4f5DqDcIi/uoVHAVYNFOEjnvwQPOFAU77NL+znQl3LiwcX/D2zjtfWrub6WGkDj3MKmP/MaTq923g3q6aF/5jh9ZkEMRKgqHLM8cjs30J/vITs7rS3D0lqitCLaADIxWDQoPDWiKRYPVPsprKnNwTlirjwwWstfnkSnVVhoMnxbZ3HU4LWaor5qiY++/uPTiHHNjH4ksxgTTmfOcw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Aug 13, 2026 at 10:27:09AM +0100, Lorenzo Stoakes (ARM) wrote: > On Tue, Aug 11, 2026 at 01:31:54PM -0700, Shakeel Butt wrote: > > Syzbot reported [1] a set_mm_walk() warning from kswapd. Soft limit > > reclaim is the only thing that runs shrink_lruvec() from kswapd with a > > target memcg set, and thus the only way kswapd can reach > > lru_gen_shrink_lruvec() and in turn set_mm_walk(). The offender, > > mem_cgroup_shrink_node(), has long carried a "Only used by soft limit > > reclaim. Do not reuse for anything else." comment and a priority hack, > > and it simply never got taught about MGLRU. > > > > Rather than teach it, let's delete it. The v1 soft limit was deprecated > > in v6.12 by commit 569c4f62d84a ("memcg: initiate deprecation of v1 > > soft limit"). Nobody has reported depending on it in the ~21 months > > since, and v2 has covered the same ground for a long time with > > memory.low and memory.min. > > > > Link: https://lore.kernel.org/all/6a7a6929.b50370da.49fe0.005e.GAE@google.com/ [1] > > > > Shakeel Butt (9): > > memcg: make the v1 soft limit knob inert > > memcg: remove v1 soft limit reclaim > > memcg: remove mem_cgroup_shrink_node() > > memcg: remove the soft limit reclaim tracepoints > > memcg: remove the soft limit rbtree > > memcg: remove lru_gen_soft_reclaim() > > memcg: remove the per-node soft limit tree fields > > memcg: remove mem_cgroup->soft_limit > > memcg: simplify v1 event ratelimiting > > > > .../admin-guide/cgroup-v1/memory.rst | 49 +- > > include/linux/memcontrol.h | 27 -- > > include/linux/mmzone.h | 30 +- > > include/trace/events/vmscan.h | 14 - > > mm/internal.h | 4 - > > mm/memcontrol-v1.c | 435 ++---------------- > > mm/memcontrol-v1.h | 12 +- > > mm/memcontrol.c | 7 +- > > mm/vmscan.c | 96 +--- > > 9 files changed, 66 insertions(+), 608 deletions(-) > > This is a gorgeous diffstat :) > > Obviously not my area but looking over it, all LGTM so feel free to add: > > Acked-by: Lorenzo Stoakes (ARM) > > To the whole series! Thanks for the review.