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Tue, 30 Apr 2024 10:06:33 +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 sKHqFqnCMGbaawAAD6G6ig (envelope-from ); Tue, 30 Apr 2024 10:06:33 +0000 Message-ID: Date: Tue, 30 Apr 2024 12:06:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/3] mm: fix nested allocation context filtering Content-Language: en-US To: Dave Chinner , linux-mm@kvack.org, linux-xfs@vger.kernel.org Cc: akpm@linux-foundation.org, hch@lst.de, osalvador@suse.de, elver@google.com, andreyknvl@gmail.com References: <20240430054604.4169568-1-david@fromorbit.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+fMgqZkBQJkBREIBQkRadznAAoJECJPp+fMgqZkNxIQ ALZRqwdUGzqL2aeSavbum/VF/+td+nZfuH0xeWiO2w8mG0+nPd5j9ujYeHcUP1edE7uQrjOC Gs9sm8+W1xYnbClMJTsXiAV88D2btFUdU1mCXURAL9wWZ8Jsmz5ZH2V6AUszvNezsS/VIT87 AmTtj31TLDGwdxaZTSYLwAOOOtyqafOEq+gJB30RxTRE3h3G1zpO7OM9K6ysLdAlwAGYWgJJ V4JqGsQ/lyEtxxFpUCjb5Pztp7cQxhlkil0oBYHkudiG8j1U3DG8iC6rnB4yJaLphKx57NuQ PIY0Bccg+r9gIQ4XeSK2PQhdXdy3UWBr913ZQ9AI2usid3s5vabo4iBvpJNFLgUmxFnr73SJ KsRh/2OBsg1XXF/wRQGBO9vRuJUAbnaIVcmGOUogdBVS9Sun/Sy4GNA++KtFZK95U7J417/J Hub2xV6Ehc7UGW6fIvIQmzJ3zaTEfuriU1P8ayfddrAgZb25JnOW7L1zdYL8rXiezOyYZ8Fm ZyXjzWdO0RpxcUEp6GsJr11Bc4F3aae9OZtwtLL/jxc7y6pUugB00PodgnQ6CMcfR/HjXlae h2VS3zl9+tQWHu6s1R58t5BuMS2FNA58wU/IazImc/ZQA+slDBfhRDGYlExjg19UXWe/gMcl De3P1kxYPgZdGE2eZpRLIbt+rYnqQKy8UxlszsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZAUSmwUJDK5EZgAKCRAiT6fnzIKmZOJGEACOKABgo9wJXsbWhGWYO7mD 8R8mUyJHqbvaz+yTLnvRwfe/VwafFfDMx5GYVYzMY9TWpA8psFTKTUIIQmx2scYsRBUwm5VI EurRWKqENcDRjyo+ol59j0FViYysjQQeobXBDDE31t5SBg++veI6tXfpco/UiKEsDswL1WAr tEAZaruo7254TyH+gydURl2wJuzo/aZ7Y7PpqaODbYv727Dvm5eX64HCyyAH0s6sOCyGF5/p eIhrOn24oBf67KtdAN3H9JoFNUVTYJc1VJU3R1JtVdgwEdr+NEciEfYl0O19VpLE/PZxP4wX PWnhf5WjdoNI1Xec+RcJ5p/pSel0jnvBX8L2cmniYnmI883NhtGZsEWj++wyKiS4NranDFlA HdDM3b4lUth1pTtABKQ1YuTvehj7EfoWD3bv9kuGZGPrAeFNiHPdOT7DaXKeHpW9homgtBxj 8aX/UkSvEGJKUEbFL9cVa5tzyialGkSiZJNkWgeHe+jEcfRT6pJZOJidSCdzvJpbdJmm+eED w9XOLH1IIWh7RURU7G1iOfEfmImFeC3cbbS73LQEFGe1urxvIH5K/7vX+FkNcr9ujwWuPE9b 1C2o4i/yZPLXIVy387EjA6GZMqvQUFuSTs/GeBcv0NjIQi8867H3uLjz+mQy63fAitsDwLmR EP+ylKVEKb0Q2A== In-Reply-To: <20240430054604.4169568-1-david@fromorbit.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: pgigwb1fh946kd1z7kw7wch9zowfsb3i X-Rspamd-Queue-Id: AA19B40019 X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1714471595-557115 X-HE-Meta: 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 AvHl35Xe BuBKMWjN6GILWtXGPilUWPao6ywJ7EDWQWonXR/pkeyHqSXYpyqO6/sA0NNsN3GlGXFJJkYL1TdhUI2fWBbJli2EpHtSC1ZFOtz9pBr7tKsHMRkHD++4E94E4jwyExXUGaB2WxnZU9zuUpEOzXGRIumcnWsEGIBjGBwAPvoy/nATu3SR8l3ROS6EjBiqD/nzYVDS63BL12rUHzKSLezIQz48Xb50aPoh1hiOY7P3gpgXOfkMHN2X+Qpdf2J8DDrKpIEUlychRGhLwdaV2bQ5UHx+0S/rcs7qI3BqipSbv5Www7b5v4txYoKmqCGrxUCUI0ECR 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 4/30/24 7:28 AM, Dave Chinner wrote: > This patchset is the followup to the comment I made earlier today: > > https://lore.kernel.org/linux-xfs/ZjAyIWUzDipofHFJ@dread.disaster.area/ > > Tl;dr: Memory allocations that are done inside the public memory > allocation API need to obey the reclaim recursion constraints placed > on the allocation by the original caller, including the "don't track > recursion for this allocation" case defined by __GFP_NOLOCKDEP. > > These nested allocations are generally in debug code that is > tracking something about the allocation (kmemleak, KASAN, etc) and > so are allocating private kernel objects that only that debug system > will use. > > Neither the page-owner code nor the stack depot code get this right. > They also also clear GFP_ZONEMASK as a separate operation, which is > completely redundant because the constraint filter applied > immediately after guarantees that GFP_ZONEMASK bits are cleared. > > kmemleak gets this filtering right. It preserves the allocation > constraints for deadlock prevention and clears all other context > flags whilst also ensuring that the nested allocation will fail > quickly, silently and without depleting emergency kernel reserves if > there is no memory available. > > This can be made much more robust, immune to whack-a-mole games and > the code greatly simplified by lifting gfp_kmemleak_mask() to > include/linux/gfp.h and using that everywhere. Also document it so > that there is no excuse for not knowing about it when writing new > debug code that nests allocations. > > Tested with lockdep, KASAN + page_owner=on and kmemleak=on over > multiple fstests runs with XFS. Reviewed-by: Vlastimil Babka Thanks.