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Tue, 23 Dec 2025 23:47:07 +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 EXz0JvspS2kUXgAAD6G6ig (envelope-from ); Tue, 23 Dec 2025 23:47:07 +0000 Message-ID: <0b5f2c87-c180-4ada-9d37-f2e3d0071d9f@suse.cz> Date: Wed, 24 Dec 2025 00:47:07 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/mempool.c: set @elems slots to NULL once freed To: klourencodev@gmail.com, linux-mm@kvack.org, Christoph Hellwig Cc: akpm@linux-foundation.org References: <20251223231054.16061-1-klourencodev@gmail.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: <20251223231054.16061-1-klourencodev@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 2D6DAC000C X-Stat-Signature: jxs69pgbe1fs4quk54x1qhdksirzt88a X-Rspam-User: X-HE-Tag: 1766533630-189862 X-HE-Meta: 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 udleBjYd m2VjJ+IipkK6desDRNmh6j4SbFjf43t+mpdYgUPmFWsy4HrkhMaedTU0+USGdMMvxAWQE3sdODcDmnOJm2InN3aNFAJgZCW7vjCPA4+g3fYZPvfhMGYZNfPwDYLZHJxF3e8+kQPmuqkZcgu6unBacQGeRJsiFYKjHh6UTiFBFeKJaB/ospOwIwPnxO0ZPGfSlZsy9AhjGg8vwkXl/9aonP8SiV/Gze41PGOIW0mNUE+kH20tI9vSBTja/zJnt+8ZJjCTgF0eMtCJmgUhWKoFPBrwPsxcHpkKCbyVItOUlo//J2Kc8+yGI0AFaag== 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: +Cc Christoph On 12/24/25 00:10, klourencodev@gmail.com wrote: > From: Kevin Lourenco > > This is documented in the function comment as "...and sets their > slots in @elems to NULL.", but it was not followed. > > We need to follow the NULL assignment, because elements newly returned > to the pool must not be touched under any circumstances by the user. > > Signed-off-by: Kevin Lourenco > --- > mm/mempool.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/mm/mempool.c b/mm/mempool.c > index c290e5261b47..1a2060304fd4 100644 > --- a/mm/mempool.c > +++ b/mm/mempool.c > @@ -674,7 +674,8 @@ unsigned int mempool_free_bulk(struct mempool *pool, void **elems, > if (unlikely(READ_ONCE(pool->curr_nr) < pool->min_nr)) { > spin_lock_irqsave(&pool->lock, flags); > while (pool->curr_nr < pool->min_nr && freed < count) { > - add_element(pool, elems[freed++]); > + add_element(pool, elems[freed]); > + elems[freed++] = NULL; > added = true; > } > spin_unlock_irqrestore(&pool->lock, flags); > @@ -683,7 +684,8 @@ unsigned int mempool_free_bulk(struct mempool *pool, void **elems, > /* Handle the min_nr = 0 edge case: */ > spin_lock_irqsave(&pool->lock, flags); > if (likely(pool->curr_nr == 0)) { > - add_element(pool, elems[freed++]); > + add_element(pool, elems[freed]); > + elems[freed++] = NULL; > added = true; > } > spin_unlock_irqrestore(&pool->lock, flags);