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Mon, 13 Apr 2026 14:20:09 +0800 (CST) X-Zmail-TransId: 2afa69dc8b19fd6-934e4 X-Mailer: Zmail v1.0 Message-ID: <20260413142009771oJn6KdfOwqg6hop17-6bF@zte.com.cn> In-Reply-To: References: adxm5az9EfHr2aYg@hyeyoo,20260413131423382u868NVr2RkcvDe0Ii3ERj@zte.com.cn,adx-2p09xEKz5Zdb@hyeyoo Date: Mon, 13 Apr 2026 14:20:09 +0800 (CST) Mime-Version: 1.0 From: To: Cc: , , , , , , , , , , , Subject: =?UTF-8?B?UmU6IFtQQVRDSCB2NV0gbW0vc2x1YjogZGVmZXIgZnJlZWxpc3QgY29uc3RydWN0aW9uIHVudGlsIGFmdGVyIGJ1bGsgYWxsb2NhdGlvbiBmcm9tIGEgbmV3IHNsYWI=?= Content-Type: text/plain; charset="UTF-8" X-MAIL:mse-fl2.zte.com.cn 63D6K80N002563 X-TLS: YES X-SPF-DOMAIN: zte.com.cn X-ENVELOPE-SENDER: hu.shengming@zte.com.cn X-SPF: None X-SOURCE-IP: 10.5.228.133 unknown Mon, 13 Apr 2026 14:20:19 +0800 X-Fangmail-Anti-Spam-Filtered: true X-Fangmail-MID-QID: 69DC8B23.000/4fvHMR4m1sz7QYS1 X-Rspam-User: X-Rspamd-Queue-Id: A98A94000E X-Stat-Signature: gdzxegm3sdiy8x3ihrrhejda5uh7mu5f X-Rspamd-Server: rspam06 X-HE-Tag: 1776061224-748559 X-HE-Meta: U2FsdGVkX18uuNhJtKqEykflnU9qyrKv4yiecTu7VESxLKgYfGwxCiyBVRn3xhtLpqBFw8nDIXU5wbtSnnd0dQjEP+OYVm5za7/fs+HoUkWVSDMLXUqjVg6reEh8nb2/8qSo4wuS/THtpPgDCyyfvsuOBVKqJOiOhDPOykEe0/K7MRXe5YjJcOgtGBclvk31mA/5V4YMTKiT2pArO2QiUsRzVcQu8b3wRis/5e0pr/i/BDZmW0TIceWx9WNX2Y2lCVLiod4q0cBlim0MWliSho0d7prhk7HQUR5h8mGztvpfBcz1Xosgq6v/hFvsntOMBfbUHCQ11m7tBCu0B7AdnYo9LYwd18llODKCYDGjTj5+cjCqIi/QPZajQ4XBMkjJOwrzk9XSquF/8BbJYj8zDwbZXIHPIlEAue8HXtU7GPv9aTjkpvyvVxQq7Ptm/Ezz1we8d6EllPIECnM0CQF9tAB1aPHlBigsKkH8PvsV/M4lctjzQu406F1JM75PxRmbJFdU679wSGThhvz4n95ID36hZLD0KKlnW92DjqqUwevRUJsDpyU/SsbyiijS03+y229/MlnYNamOyNJkdQOXDMg+J1uicbONGSJqmBTSi3n4IKa2BzfmTu4LpwuXWFwltL0CZ18IAmf/a+xN5p5nWufj0OOP7khG7VnEg0GUDxZiqQA5LChjwZ1nXltl0e6/59oQdsXSiixvKLzgvLgtv4fq4/hJXS0patYPADKmPPo6GVdMkCDtusmMvIw6rqB6CUlbLpWUvsH2r8HL4v+HW/YssukkBgK+Ap9xAvFpwHaTc/di/OvJMfc0PwiWEHOdmZocNzSElqJ0dSnIkHoIPsXzkCnwpMACJNersQsV1a7/q1eIm4eUiXaQaSg5xK4fZqfwWhu0nbK9AMa+w0l6dRqSUxPxMfbE6gQiivOFUE01SSW6ng4Asd99sStHqFowKno7Dd2V+Sfd4D+WXfu /sLwJqMT /MoyrVq3FGewkkdVllTLM04MNdfEDIXuDf12Nwo9EqtpaxXYg+wqXwWqHeIAxfjJOJU581CNBQZbxUaS3ux0XJI6O5GBfyfpA0RWkXEEc3Gl3ftKtkfnWyNvgmHifllvkaVUxqHGuRrndlJvQ/oEz7Xd4XKXpl9OH3pAgcDMyXBYJEXq6eF+/HfuK1MkdGXuqjuRI1OK077vLIjYFwvD9YGtC+ks2c4H4VCBI7/UGvlFWF5jAciqgnBEheA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Harry wrote: > On Mon, Apr 13, 2026 at 01:14:23PM +0800, hu.shengming@zte.com.cn wrote: > > Harry wrote: > > > On Thu, Apr 09, 2026 at 08:43:52PM +0800, hu.shengming@zte.com.cn wrote: > > > > From: Shengming Hu > > > > [...] > > > > - inc_slabs_node(s, nid, slab->objects); > > > > spin_unlock_irqrestore(&n->list_lock, flags); > > > > > > > > + inc_slabs_node(s, slab_nid(slab), slab->objects); > > > > > > Ouch, I didn't catch this when it was added in v4. When slab debugging > > > feature is enabled for the cache, inc_slabs_node() should be done within > > > the spinlock to avoid race conditions with slab validation. > > > > > > Perhaps it's worth adding a comment mentioning this :) > > > > > > See commit c7323a5ad078 ("mm/slub: restrict sysfs validation to debug > > > caches and make it safe") for more details. > > > > > > With this fixed, please feel free to add: > > > Reviewed-by: Harry Yoo (Oracle) > > > > > > > You are right about the inc_slabs_node() placement. I missed that change when > > it was introduced in v4. Thank you very much for catching it. > > > > After reading commit c7323a5ad078 ("mm/slub: restrict sysfs validation to debug > > caches and make it safe"), my understanding is that inc_slabs_node() should > > remain under n->list_lock for debug caches, so that validation cannot observe > > inconsistent state during list transitions. I will fix that in the next revision > > and add a comment along these lines. > > > > Would a comment like the following look good? :-) > > > > /* > > * Debug caches require nr_slabs updates under n->list_lock so validation > > * cannot race with list transitions and observe inconsistent state. > > */ > > Mostly LGTM, but perhaps it's better to say > "validation cannot race with slab (de)allocations" > because it's not about transitions between lists, > but rather about slabs being added to or removed from the node while > validation code is iterating over partial and full lists. > > Thanks! > Thanks, that makes sense. You're right that the issue is better described in terms of slab (de)allocations rather than list transitions. I'll update the comment. -- Cheers, Shengming