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Mon, 1 Sep 2025 08:15:04 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id xhphHAhWtWjoVgAAD6G6ig (envelope-from ); Mon, 01 Sep 2025 08:15:04 +0000 Message-ID: <7f30ddd1-c6f7-4b2b-a2b9-875844092e28@suse.cz> Date: Mon, 1 Sep 2025 10:15:04 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] mm: slub: avoid wake up kswapd in set_track_prepare Content-Language: en-US To: David Rientjes , yangshiguang1011@163.com Cc: harry.yoo@oracle.com, akpm@linux-foundation.org, cl@gentwo.org, roman.gushchin@linux.dev, glittao@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, yangshiguang , stable@vger.kernel.org References: <20250830020946.1767573-1-yangshiguang1011@163.com> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; 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 BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: A359A1C0009 X-Stat-Signature: yhfgzyc5s5zb8urw63gmwhh7ajuhpsru X-Rspam-User: X-HE-Tag: 1756714506-569441 X-HE-Meta: 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 qemAvQDg szgjaqdrGmlhETeD32zqOADCNSxdZu5q+0t4eq202MH15fc7giDngbL9+HesaguuDiDOgbnRmXc3ekSo2Wr/J6D+/7XXdNp7YmkbMp9LFjThDsHkLOyYUV912wdJszZYnIyvwWShC3m80jT1C6JqnG8/9o8shkxNRoiFCCGTeERC6+huD9rSgn8G0/H5uwYEPLKRuPYI9V9i+U7g0f4xdMuCq0CRyBWk7EmxuSi7iFTxye07dEshWPeJubxeJz/kxvL6QkmqGE6sHwT7E+Qgs8yf7pEHY/2WUMR2gPQvmG9EoKWRTb2b49A3ltq1LQciBZve7xeCTNCmBksCl5kyV7en9DkGBptWgHAzUA2xnA/34Yz33s/19EaByyJvo4GOD5WPM X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/1/25 09:50, David Rientjes wrote: > On Sat, 30 Aug 2025, yangshiguang1011@163.com wrote: > >> From: yangshiguang >> >> From: yangshiguang >> > > Duplicate lines. > >> set_track_prepare() can incur lock recursion. >> The issue is that it is called from hrtimer_start_range_ns >> holding the per_cpu(hrtimer_bases)[n].lock, but when enabled >> CONFIG_DEBUG_OBJECTS_TIMERS, may wake up kswapd in set_track_prepare, >> and try to hold the per_cpu(hrtimer_bases)[n].lock. >> >> Avoid deadlock caused by implicitly waking up kswapd by >> passing in allocation flags. And the slab caller context has >> preemption disabled, so __GFP_KSWAPD_RECLAIM must not appear in gfp_flags. >> > > This mentions __GFP_KSWAPD_RECLAIM, but the patch actually masks off > __GFP_DIRECT_RECLAIM which would be a heavierweight operation. Disabling > direct reclaim does not necessarily imply that kswapd will be disabled as > well. Yeah I think the changelog should say __GFP_DIRECT_RECLAIM. > Are you meaning to clear __GFP_RECLAIM in set_track_prepare()? No because if the context context (e.g. the hrtimers) can't support __GFP_KSWAPD_RECLAIM it won't have it in gfp_flags and we now pass them to set_track_prepare() so it already won't be there.