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Wed, 5 Nov 2025 08:09:23 +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 fDUHHDMGC2mPSwAAD6G6ig (envelope-from ); Wed, 05 Nov 2025 08:09:23 +0000 Message-ID: <190f06d4-022c-45f2-abd8-66dfc20223e5@suse.cz> Date: Wed, 5 Nov 2025 09:09:23 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/page_alloc: don't warn about large allocations with __GFP_NOFAIL To: libaokun@huaweicloud.com, linux-mm@kvack.org Cc: akpm@linux-foundation.org, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, willy@infradead.org, shakeel.butt@linux.dev, jack@suse.cz, yi.zhang@huawei.com, yangerkun@huawei.com, libaokun1@huawei.com References: <20251105074106.3508870-1-libaokun@huaweicloud.com> Content-Language: en-US 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: <20251105074106.3508870-1-libaokun@huaweicloud.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 8ADB4C000F X-Stat-Signature: ttztybj8swq9q6aik41z5sm37kgbe18g X-Rspam-User: X-HE-Tag: 1762330165-92710 X-HE-Meta: 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 fQio+hT8 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 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 11/5/25 08:41, libaokun@huaweicloud.com wrote: > From: Baokun Li > > Filesystems use __GFP_NOFAIL to allocate block-sized folios for metadata > reads at critical points, since they cannot afford to go read-only, > shut down, or enter an inconsistent state due to memory pressure. > > Currently, attempting to allocate page units greater than order-1 with > the __GFP_NOFAIL flag triggers a WARN_ON() in __alloc_pages_slowpath(). > However, filesystems supporting large block sizes (blocksize > PAGE_SIZE) > can easily require allocations larger than order-1. > > As Matthew Wilcox noted, if we have a filesystem with 64KiB sectors, there > will be many clean folios in the page cache that are 64KiB or larger. > > With gfp flags and order already included in the OOM report, both > Vlastimil Babka and Michal Hocko suggested that we can take the risk of > removing this warning first and then observe whether a large number of > related OOM reports appear. > > If that happens, we can consider adding special handling in other places. > > Suggested-by: Matthew Wilcox > Link: https://lore.kernel.org/all/aQPX1-XWQjKaMTZB@casper.infradead.org > Suggested-by: Vlastimil Babka > Link: https://lore.kernel.org/all/188a95ba-6384-4319-bb74-c0d9ec6c4079@suse.cz > Suggested-by: Michal Hocko > Link: https://lore.kernel.org/all/aQotQBjnDDeL_wHx@tiehlicka > Signed-off-by: Baokun Li Acked-by: Vlastimil Babka > --- > > RFC: https://lore.kernel.org/all/20251031061350.2052509-1-libaokun@huaweicloud.com > > mm/page_alloc.c | 5 ----- > 1 file changed, 5 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index fb91c566327c..e4efda1158b2 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -4683,11 +4683,6 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > int reserve_flags; > > if (unlikely(nofail)) { > - /* > - * We most definitely don't want callers attempting to > - * allocate greater than order-1 page units with __GFP_NOFAIL. > - */ > - WARN_ON_ONCE(order > 1); > /* > * Also we don't support __GFP_NOFAIL without __GFP_DIRECT_RECLAIM, > * otherwise, we may result in lockup.