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Thu, 13 Nov 2025 13:48:06 +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 XDgMGJbhFWlyeQAAD6G6ig (envelope-from ); Thu, 13 Nov 2025 13:48:06 +0000 Message-ID: Date: Thu, 13 Nov 2025 14:48:06 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: poison_element vs highmem, was Re: [linux-next:master] [block] ec7f31b2a2: BUG:unable_to_handle_page_fault_for_address Content-Language: en-US To: Oliver Sang Cc: Christoph Hellwig , Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , linux-mm@kvack.org, oe-lkp@lists.linux.dev, lkp@intel.com, Jens Axboe , "Martin K. Petersen" , Johannes Thumshirn , Anuj Gupta , Kanchan Joshi , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <202511111411.9ebfa1ba-lkp@intel.com> <20251111074828.GA6596@lst.de> 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: rspam05 X-Rspamd-Queue-Id: 938CC160006 X-Stat-Signature: 8ncfkidfg8d39mx54ugywxqm8aub4epx X-Rspam-User: X-HE-Tag: 1763041688-64173 X-HE-Meta: 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 WLh7wDYU Wx/4EdyVtbZ5a+PJfXbRX8oUmbgjxoRHg7AVFX3oQFOiTRw992RmYwcihsWngw4cmtfTBzxM1qPmw34dZSK15q2Qsh0ryltfyLjjbufECoNOuFCZXYw0Vr5kcYakG1a9/oeh9lpWi9cDZkH71nfIx9Q0J5bpQgngODlWRrqJNut07DPKtFhCAo0E7JON1hZBKm0JOgf+kx8NFNgFUlI+mjq0/lkDwmbToeFLmYaLCqQ2aFM3PzJz/0gnntVXjBOaRHHUYRcw2LJOy9gT0h8ZiEy5iv3ds209XJHW1BxwmVYGpcDlYNoqVjYVzVvVoZ6PZGeKmTw+5O6a0L+t/tYqJ9JNQR+fL0CPtxbaYYUNA07FmjydywhGFsk4HfPaQ7nMNfKTB 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 11/13/25 08:44, Oliver Sang wrote: > hi, Vlastimil Babka, > > On Wed, Nov 12, 2025 at 10:33:32AM +0100, Vlastimil Babka wrote: >> On 11/11/25 08:48, Christoph Hellwig wrote: >> > Looks like this is due to the code in poison_element, which tries >> > to memset more than PAGE_SIZE for a single page. This probably >> > implies we are the first users of the mempool page helpers for order > 0, >> > or at least the first one tested by anyone on 32-bit with highmem :) >> > >> > That code seems to come from >> > >> > commit bdfedb76f4f5aa5e37380e3b71adee4a39f30fc6 >> > Author: David Rientjes >> > Date: Wed Apr 15 16:14:17 2015 -0700 >> > >> > mm, mempool: poison elements backed by slab allocator >> > >> > originally. The easiest fix would be to just skip poisoning for this >> > case, although that would reduce the usefulness of the poisoning. >> >> #syz test > > we applied below patch upon ec7f31b2a2 directly, and confirmed the issue we > reported gone now with the patch. > > Tested-by: kernel test robot Thanks! > BTW, we are kernel test robot, not the syzbot :) thanks Yeah I realized only after sending... I'll make this a full patch then. How urgent is it, Christoph? I suppose this is related to the bulk mempool changes, and we discussed the users will target 6.20 (7.0?) merge window? So landing this fix in 6.19 is enough? >> ----8<---- >> From 4d97b55c208c611cb01062e0fbf9dbda9f5617d5 Mon Sep 17 00:00:00 2001 >> From: Vlastimil Babka >> Date: Wed, 12 Nov 2025 10:29:52 +0100 >> Subject: [PATCH] mm/mempool: fix poisoning order>0 pages with HIGHMEM >> >> Signed-off-by: Vlastimil Babka >> --- >> mm/mempool.c | 28 ++++++++++++++++++++++------ >> 1 file changed, 22 insertions(+), 6 deletions(-) >> >> diff --git a/mm/mempool.c b/mm/mempool.c >> index 1c38e873e546..75fea9441b93 100644 >> --- a/mm/mempool.c >> +++ b/mm/mempool.c >> @@ -68,10 +68,18 @@ static void check_element(mempool_t *pool, void *element) >> } else if (pool->free == mempool_free_pages) { >> /* Mempools backed by page allocator */ >> int order = (int)(long)pool->pool_data; >> - void *addr = kmap_local_page((struct page *)element); >> +#ifdef CONFIG_HIGHMEM >> + for (int i = 0; i < (1 << order); i++) { >> + struct page *page = (struct page *)element; >> + void *addr = kmap_local_page(page + i); >> >> - __check_element(pool, addr, 1UL << (PAGE_SHIFT + order)); >> - kunmap_local(addr); >> + __check_element(pool, addr, PAGE_SIZE); >> + kunmap_local(addr); >> + } >> +#else >> + void *addr = page_address((struct page *)element); >> + __check_element(pool, addr, PAGE_SIZE << order); >> +#endif >> } >> } >> >> @@ -97,10 +105,18 @@ static void poison_element(mempool_t *pool, void *element) >> } else if (pool->alloc == mempool_alloc_pages) { >> /* Mempools backed by page allocator */ >> int order = (int)(long)pool->pool_data; >> - void *addr = kmap_local_page((struct page *)element); >> +#ifdef CONFIG_HIGHMEM >> + for (int i = 0; i < (1 << order); i++) { >> + struct page *page = (struct page *)element; >> + void *addr = kmap_local_page(page + i); >> >> - __poison_element(addr, 1UL << (PAGE_SHIFT + order)); >> - kunmap_local(addr); >> + __poison_element(addr, PAGE_SIZE); >> + kunmap_local(addr); >> + } >> +#else >> + void *addr = page_address((struct page *)element); >> + __poison_element(addr, PAGE_SIZE << order); >> +#endif >> } >> } >> #else /* CONFIG_SLUB_DEBUG_ON */ >> -- >> 2.51.1 >> >>