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Mon, 1 Sep 2025 09:14:51 +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 493KAwtktWhvagAAD6G6ig (envelope-from ); Mon, 01 Sep 2025 09:14:51 +0000 Message-ID: Date: Mon, 1 Sep 2025 11:14:50 +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: yangshiguang Cc: David Rientjes , 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> <7f30ddd1-c6f7-4b2b-a2b9-875844092e28@suse.cz> <11922bd5.7fae.1990464d9c8.Coremail.yangshiguang1011@163.com> <623a8fd2.8b7b.1990481f065.Coremail.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: <623a8fd2.8b7b.1990481f065.Coremail.yangshiguang1011@163.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: cgxghxj19e9z9prz45zyrt8mc14q8n87 X-Rspam-User: X-Rspamd-Queue-Id: 380568000B X-Rspamd-Server: rspam01 X-HE-Tag: 1756718092-602168 X-HE-Meta: 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 hQFWM7YQ 99OejtitYDkn6mvHN3K+/7T3Gqj93hNE5ezc8yOkbSodY+r1y/IYCk+hKcsl7SftwcKt04U+c6RUhEpBGzjqaNldO2N8EXmWadlruRfvji7BlJ0VsSMG2ejmWIOf0cbOLMZ44iXnN1NBfxaaHg7Io1vlDjAo0tB6wJgvs+GWN1JjqsQ5JR8CrghB87He3LdZ0TLtj1O+8dPryCIC9SvNDgyWpCwd8m/3CHXRjTgl8ayg2mO0DmXGNUxDHiSFsHmkzgsIYYcf3WBILYOganFgcW0kyikgvi2nTOwGj/R315cDu0N/pXhTVov8y5ub27rrCaD8ZfO5PAitfylGFbUHpA4lUW/8lMLoRGWM4sEXwM5aLoR4jnVz12w4mgTuYQfkky6j/ 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 11:00, yangshiguang wrote: > > > At 2025-09-01 16:46:13, "Vlastimil Babka" wrote: >>On 9/1/25 10:29, yangshiguang wrote: >>> >>> >>> At 2025-09-01 16:15:04, "Vlastimil Babka" wrote: >>>>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. >>> >>> >>> Sry. Should be __GFP_DIRECT_RECLAIM. I will resend the patch. >> >>I have adjusted it locally already. Also moved the masking of >>__GFP_DIRECT_RECLAIM to ___slab_alloc itself as that's where >>the preemption is disabled so it's more obvious. >> >>Does the result look good to you? > > This looks good. > Currently only ___slab_alloc disables preemption context calls to set_track. > In the future, not all callers will disable preemption. Great, added to slab/for-next-fixes. Thanks!