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b=MOh/46620tT8hSHj6p/BSKgS94jECE/HC4cUhJ+8nmae+Iz9xMIvr1U+hrnfKv8ek hO4IbTNLytAwdbfb6QS7Gqf4KepMbYFy/+ZW7ORJMm3eJPd2tPTfwSHuPSlpBc8CVu k5c32H2Sq2AHvh4Hiyn4erLAtAPrYvj3ScgDWY+etN6t34d1Cgr9WviBAFIRpkc7+Z Vm8LMGuZbLY8p+ymN8vNqn0LQhz5BHcbBBJBacAvmqfVPUYf/6gevXxuxhfE7sKKYj 4Onfq6euYjNuPG/n9PLMUIWddt3boORc71rGTZNVj2kyB9fNhAXu32PdY0Y/4K3fHP RxYYHotVl2i6w== Message-ID: Date: Wed, 29 Jul 2026 18:21:19 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm/slub: fix missing debugfs entries for caches created before sysfs init Content-Language: en-US To: Li Xiasong , Harry Yoo , Andrew Morton Cc: stable@vger.kernel.org, Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Rasmus Villemoes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, yuehaibing@huawei.com, zhangchangzhong@huawei.com, weiyongjun1@huawei.com References: <20260729101849.3734287-1-lixiasong1@huawei.com> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSNWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBrZXJuZWwub3JnPsLBsAQTAQoAWhYhBKlA1DSZLC6OmRA9UCJPp+fM gqZkBQJqFFy6GxSAAAAAAAQADm1hbnUyLDIuNSsxLjEyLDIsMgIbAwUJGtCBUAULCQgHAwUV CgkICwUWAgMBAAIeBQIXgAAKCRAiT6fnzIKmZJIUEADFx/tREzUImHrEwVHeSvDFmA7tJysI UVrlvrM09E7GIuzphzv7jYmo8n3ANpCczLEVr4G0syYQdTigaZgv3+FQDIIzhKih1IHhu1Ei XHlywNWKnQxxQEUNi5Mwx43wQz5XVw9F1A7gtKBKNtfogO511hAbrzagrYajyQacEJ/+sfhZ 9Da8ltHIXD8pcYaHUfQgEusCgmEd9+KrUwrTbckFKmYq5chuE6yJ4J0EmWknL096jIE6CnzF FRslQ3B1UKDjxVsm1ZHfir5NeWszLkTvGFsddFaWTgh8UycESG6VQzKXjjewXu2pG7YQYRpj QKm1W5X2TkwWkXRBZTmfmbhxIUMh3+zf5wQ463rSmDN/8v81tdqBtAW6rH/kzg1GvkaTHXn0 507yEHFzBksk2viAuIxxr7km8+/KARYLIdGtx30EG8cKzAUZOK6WqxtNCsXUJNrVE8CWrCaD icoNu7Fs1c5hmPHdSTnU48ce67449DdnO4neLSNhRiGlMHJgfJUmgrxu/hcYeOZ3haWmEQ2w uW1Mh01OHi8QZHCEyAbABrPs9GUgccc/4eYXX9hIgxfSkYzn8f+8NuIFPWl/0uTvjgqU29FQ SbzOLxHq9439Ox40G5mS5eZXRGxITYR+6TXvRGI6P/264jvflnr/pDGUttaikU+0W+1uxgKH cmYbEc7ATQRbGTU1AQgAn0H6UrFiWcovkh6EXVcl+SeqyO6JHOPm+e9Wu0Vw+VIUvXZVUVVQ La1PQDUi6j00ChlcR66g9/V0sPIcSutacPKfdKYOBvzd4rlhL8rfrdEsQw5ApZxrA8kYZVMh FmBRKAa6wos25moTlMKpCWzTH84+WO5+ziCTsTUZASAToz3RdunTD+vQcHj0GqNTPAHK63sf bAB2I0BslZkXkY1RLb/YhuA6E7JyEd2pilZOrIuBGl/5q2qSakgnAVFWFBR/DO27JuAksYnq +aH8vI0xGvwn75KqSk4UzAkDzWSmO4ZHuahKtQgZNsMYV+PGayRBX9b9zbldzopoLBdqHc4n jQARAQABwsF8BBgBCgAmAhsMFiEEqUDUNJksLo6ZED1QIk+n58yCpmQFAmfIHFQFCRYU6J8A CgkQIk+n58yCpmS2PA//bqN1LfcotmArgElsa+0EGZSQlYgK48pm8WAeTXTngudP9IJ4SuKY HR5RNjHcBeqN+Me0zxRqYzRb8nGanHEkDyf4Im8DQM8d6vbyU+FcPmG4skud4kgS1zMHnlVd SXfSIwKC/hKgdHG8aBV7545Lz9X6Iohea+94wneD0aw/hqF+QWewGZhWJriWAZtvEkzNjQOi 4U9F/trLten/x7bpphDSnDMKJtITbtzATT1Dq7o7VpIUK1nCTQALMuMjKCdi8OdU/+V+R3O4 0PXWvX8qrvqYapVbZ+9KqT74FsuB0Ya9uXwgBF2Q6cRuETZk5vqaqKxzqoQZCO8AOz/58j6O 2RHNy/mZEN+7tJ5Tsq42zVJ4jxsT8b9YplavCMsnBgDeRWhcbYhCyttoL7nYISyWg4kQYZ/P wIV3OuNv2f8iKYsxNsRuClOAF82+gvqOy1/1pprFjy8uo2pkoOrb63aOP3vO5VHnRKgra6dq NcaZ+c6J4H+nEJGi2SkHAUJz5oBzuThvPudLvPA/SK8sKoM01IRxSihev/S/5WLazXB1PGem OCbvzC1IjWJJraxiDJ5IygokapUa2RP7+WBR22skQ3SSl6G107QgWKSyTOGWEaRmV53vxQLV jXuCmzSSasTL60zq5yGrT4/DYQVSNEUiUbG4pYekxJujNeEDkUlky0Y= In-Reply-To: <20260729101849.3734287-1-lixiasong1@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 5BEE14000F X-Rspam-User: X-Stat-Signature: ficodaxbz4icyc68ux39g58bdfk33waq X-HE-Tag: 1785342084-411390 X-HE-Meta: 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 zDAgm9ki uMVbaNUxFCbdb/SkcKcqnOzPRvx4n78wakbie/KhDLtoG27jBn8D4/0JClJu/xcSdFQnoTqX2e7WxsBx3nLdxIZbaFBzXXeauGRmCRORyCZpzf77iBOGWR4kVyxxFNKO0h9hWQHLYTG/6OXaZK+QpcL6dbdebUYy4Cn6NYzNCDYNWQP6kdKB4IJRolvnYjY45+TqkZJJ6IPLm0e3q6UUKB/5Zb5II/aMsFbFmSBi3pHUOyE+fvK0ee/rvoG/QeX90WCJ0ovLhqeEOSRig43m7bb5eDyCApvCTq7AQPi1UDJ3h2K7AXqZtJ2olsg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/29/26 12:18, Li Xiasong wrote: > slab_debugfs_init() creates the slab debugfs root at device initcall > time, while slab_sysfs_init() moves slab_state to FULL at late initcall > time. SLAB_STORE_USER caches created in this window miss their debugfs > entries because do_kmem_cache_create() skips debugfs_slab_add() when > slab_state <= UP. This was observed with MPTCP's request_sock_subflow_v6 > cache, whose slab debugfs directory was missing. > > The affected window is: > > slab_debugfs_init() > slab_debugfs_root = debugfs_create_dir(...) > list_for_each_entry(s, &slab_caches, list) > debugfs_slab_add(s) > > kmem_cache_create(..., SLAB_STORE_USER, ...) > do_kmem_cache_create() > if (slab_state <= UP) > return without debugfs entries > > slab_sysfs_init() > slab_state = FULL > > Initialize the debugfs root and add debugfs entries while holding > slab_mutex, walking slab_caches exactly once and handling both sysfs > and debugfs entries in the same pass. This gives the sysfs and debugfs > initialization an explicit order and prevents caches from being > created between the debugfs scan and slab_state reaching FULL. > > Gate the new slab_late_init() on either sysfs or debugfs being enabled, > with the slab_kset creation and alias_list processing factored into > helpers that have empty no-sysfs variants, as suggested by Vlastimil > Babka. On slab_kset_init() failure, slab_state stays below FULL so > kmem_cache_create() keeps taking the early-boot path, matching prior > behavior. > > Guard debugfs_slab_release() against an uninitialized debugfs root, > since the root is now created later and a cache may be released before > it exists. > > Fixes: 1a5ad30b89b4 ("mm: slub: make slab_sysfs_init() a late_initcall") > Cc: stable@vger.kernel.org > Suggested-by: Vlastimil Babka > Signed-off-by: Li Xiasong Added to slab/for-next, thanks!