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Mon, 5 Jan 2026 10:42:26 +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 VF9fIZKVW2lnVAAAD6G6ig (envelope-from ); Mon, 05 Jan 2026 10:42:26 +0000 Message-ID: Date: Mon, 5 Jan 2026 11:42:26 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/3] mm: only interrupt taking all mm locks on fatal signal Content-Language: en-US To: Mikulas Patocka , Lorenzo Stoakes Cc: Alex Deucher , =?UTF-8?Q?Christian_K=C3=B6nig?= , Andrew Morton , David Hildenbrand , amd-gfx@lists.freedesktop.org, linux-mm@kvack.org, "Liam R. Howlett" , Jann Horn , Pedro Falcato , Matthew Wilcox References: 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-Queue-Id: 6E32840002 X-Rspamd-Server: rspam03 X-Stat-Signature: 7eo4uycfbuzy4rc3aouyzwrw3yb7p4hd X-Rspam-User: X-HE-Tag: 1767609748-965615 X-HE-Meta: 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 +cTGkg2Z NfdW9fMSu3iKH+4qCpaoXjRKEyJz6oE48z3hptQqRHhJZWcHYUMS77MbUxOYiZDiKZXAkJHiz8zPG0ZW7IWg/lrBYhlwWKsjgi0NphPaqRdFcJfenE4c5j3Zyc4cHhkPOGrGfA594EU1JjaJKDeMCS0IDI52bacXABt7jnmNa7/9JnaHRVDsOEq71i9PsAnd0Rj0RQXWokYtJjgHXeBkKUrzGAuuTqGBjwtc2pyLUNTe8SsVLevkrjdpQs0I+jOFlNv4ijc5ZP+6YZDnCAee1lQ8gnJD1JxTqBY1cPxZlrOhmL4S+v8nDvbbSFxT5viskhqMQvWHgFLJq7cJpLZsHs1VvNGpE6q2+dJgaqhDkUCacKNu05MMRTEDfC97mF+hehFZCTXhDluLF+NTE6aLeiAs+ql/5kcZAkYimXj/x2vpZl9b4qSZyihjN+9XfF+gmhHIjBxtPL1SgwIknzFQ95Sxq2asroXC9KDQ0 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 1/4/26 22:17, Mikulas Patocka wrote: > If a process sets up a timer that periodically sends a signal in short > intervals and if it executes some kernel code that calls > mm_take_all_locks, we get random -EINTR failures. > > The function mm_take_all_locks fails with -EINTR if there is pending > signal. The -EINTR is propagated up the call stack to userspace and > userspace fails if it gets this error. > > In order to fix these failures, this commit changes > signal_pending(current) to fatal_signal_pending(current) in > mm_take_all_locks, so that it is interrupted only if the signal is > actually killing the process. > > For example, this bug happens when using OpenCL on AMDGPU. Sometimes, > probing the OpenCL device fails (strace shows that open("/dev/kfd") > failed with -EINTR). Sometimes we get the message "amdgpu: > init_user_pages: Failed to register MMU notifier: -4" in the syslog. > > The bug can be reproduced with the following program. > > To run this program, you need AMD graphics card and the package > "rocm-opencl" installed. You must not have the package "mesa-opencl-icd" > installed, because it redirects the default OpenCL implementation to > itself. > > include > include > include > include > include > include > > define CL_TARGET_OPENCL_VERSION 300 > include > > static void fn(void) > { > while (1) { > int32_t err; > cl_device_id device; > err = clGetDeviceIDs(NULL, CL_DEVICE_TYPE_GPU, 1, &device, NULL); > if (err != CL_SUCCESS) { > fprintf(stderr, "clGetDeviceIDs failed: %d\n", err); > exit(1); > } > write(2, "-", 1); > } > } > > static void alrm(int sig) > { > write(2, ".", 1); > } > > int main(void) > { > struct itimerval it; > struct sigaction sa; > memset(&sa, 0, sizeof sa); > sa.sa_handler = alrm; > sa.sa_flags = SA_RESTART; > sigaction(SIGALRM, &sa, NULL); > it.it_interval.tv_sec = 0; > it.it_interval.tv_usec = 50; > it.it_value.tv_sec = 0; > it.it_value.tv_usec = 50; > setitimer(ITIMER_REAL, &it, NULL); > fn(); > return 1; > } > > I'm submitting this patch for the stable kernels, because this bug may > cause random failures in any code that calls mm_take_all_locks. > > Signed-off-by: Mikulas Patocka > Link: https://lists.freedesktop.org/archives/amd-gfx/2025-November/133141.html > Link: https://yhbt.net/lore/linux-mm/6f16b618-26fc-3031-abe8-65c2090262e7@redhat.com/T/#u > Cc: stable@vger.kernel.org > Fixes: 7906d00cd1f6 ("mmu-notifiers: add mm_take_all_locks() operation") Acked-by: Vlastimil Babka This makes sense to me as a backportable bugfix. But I wonder if going forward we should rather make all that locking killable instead of the hopeful checks between individual lock attempts. > > --- > mm/vma.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > Index: mm/mm/vma.c > =================================================================== > --- mm.orig/mm/vma.c 2026-01-04 21:19:13.000000000 +0100 > +++ mm/mm/vma.c 2026-01-04 21:19:13.000000000 +0100 > @@ -2166,14 +2166,14 @@ int mm_take_all_locks(struct mm_struct * > * is reached. > */ > for_each_vma(vmi, vma) { > - if (signal_pending(current)) > + if (fatal_signal_pending(current)) > goto out_unlock; > vma_start_write(vma); E.g. here I think we already added a killable variant recently? > } > > vma_iter_init(&vmi, mm, 0); > for_each_vma(vmi, vma) { > - if (signal_pending(current)) > + if (fatal_signal_pending(current)) > goto out_unlock; > if (vma->vm_file && vma->vm_file->f_mapping && > is_vm_hugetlb_page(vma)) > @@ -2182,7 +2182,7 @@ int mm_take_all_locks(struct mm_struct * > > vma_iter_init(&vmi, mm, 0); > for_each_vma(vmi, vma) { > - if (signal_pending(current)) > + if (fatal_signal_pending(current)) > goto out_unlock; > if (vma->vm_file && vma->vm_file->f_mapping && > !is_vm_hugetlb_page(vma)) > @@ -2191,7 +2191,7 @@ int mm_take_all_locks(struct mm_struct * > > vma_iter_init(&vmi, mm, 0); > for_each_vma(vmi, vma) { > - if (signal_pending(current)) > + if (fatal_signal_pending(current)) > goto out_unlock; > if (vma->anon_vma) > list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) >