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Fri, 26 Sep 2025 14:37:50 +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 yEFSCD6l1mhRbwAAD6G6ig (envelope-from ); Fri, 26 Sep 2025 14:37:50 +0000 Message-ID: <522d9c39-b0a2-4630-947b-802b0f96eaf8@suse.cz> Date: Fri, 26 Sep 2025 16:37:49 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [mm?] KCSAN: data-race in try_to_compact_pages / try_to_compact_pages Content-Language: en-US To: syzbot , akpm@linux-foundation.org, hannes@cmpxchg.org, jackmanb@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, surenb@google.com, syzkaller-bugs@googlegroups.com, ziy@nvidia.com References: <68d63689.050a0220.25d7ab.00d9.GAE@google.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+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: <68d63689.050a0220.25d7ab.00d9.GAE@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spamd-Result: default: False [-1.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; URI_HIDDEN_PATH(1.00)[https://syzkaller.appspot.com/x/.config?x=6e0c213d0735f5dd]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; MIME_TRACE(0.00)[0:+]; FUZZY_RATELIMITED(0.00)[rspamd.com]; ARC_NA(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_TLS_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[syzkaller.appspot.com:url,appspotmail.com:email,suse.cz:mid]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; TAGGED_RCPT(0.00)[20dd68d4ba19e8242c26]; RCPT_COUNT_SEVEN(0.00)[10]; REDIRECTOR_URL(0.00)[goo.gl]; SUBJECT_HAS_QUESTION(0.00)[] X-Spam-Flag: NO X-Spam-Level: X-Spam-Score: -1.80 On 9/26/25 08:45, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: cec1e6e5d1ab Merge tag 'sched_ext-for-6.17-rc7-fixes' of g.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=12448f12580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=6e0c213d0735f5dd > dashboard link: https://syzkaller.appspot.com/bug?extid=20dd68d4ba19e8242c26 > compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/10b7c8fdfdec/disk-cec1e6e5.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/cbecc36962db/vmlinux-cec1e6e5.xz > kernel image: https://storage.googleapis.com/syzbot-assets/214f107d0a3e/bzImage-cec1e6e5.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+20dd68d4ba19e8242c26@syzkaller.appspotmail.com > > ================================================================== > BUG: KCSAN: data-race in try_to_compact_pages / try_to_compact_pages > > read-write to 0xffff88823fffacf0 of 4 bytes by task 6757 on cpu 1: > compaction_deferred mm/compaction.c:149 [inline] Yeah data races for zone->compact_considered and zone->compact_order_failed can happen but are not a problem. Somebody motivated enough might annotate them. > try_to_compact_pages+0x1be/0x940 mm/compaction.c:2838 > __alloc_pages_direct_compact+0x65/0x1d0 mm/page_alloc.c:4066 > __alloc_pages_slowpath+0x360/0x5f0 mm/page_alloc.c:4787 > __alloc_frozen_pages_noprof+0x270/0x360 mm/page_alloc.c:5161 > alloc_pages_mpol+0xb3/0x250 mm/mempolicy.c:2416 > alloc_frozen_pages_noprof+0x90/0x110 mm/mempolicy.c:2487 > ___kmalloc_large_node+0x52/0x100 mm/slub.c:4317 > __kmalloc_large_node_noprof+0x16/0xa0 mm/slub.c:4348 > __do_kmalloc_node mm/slub.c:4364 [inline] > __kmalloc_noprof+0x2ab/0x3e0 mm/slub.c:4388 > kmalloc_noprof include/linux/slab.h:909 [inline] > kmalloc_array_noprof include/linux/slab.h:948 [inline] > io_vec_realloc io_uring/rsrc.c:1327 [inline] > io_import_reg_vec+0x645/0xe80 io_uring/rsrc.c:1520 > io_sendmsg_zc+0x91/0x550 io_uring/net.c:1545 > __io_issue_sqe+0xfb/0x2e0 io_uring/io_uring.c:1771 > io_issue_sqe+0x53/0x970 io_uring/io_uring.c:1794 > io_queue_sqe io_uring/io_uring.c:2023 [inline] > io_submit_sqe io_uring/io_uring.c:2283 [inline] > io_submit_sqes+0x675/0x1060 io_uring/io_uring.c:2396 > __do_sys_io_uring_enter io_uring/io_uring.c:3463 [inline] > __se_sys_io_uring_enter+0x1c1/0x1b70 io_uring/io_uring.c:3397 > __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3397 > x64_sys_call+0x2de1/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:427 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > write to 0xffff88823fffacf0 of 4 bytes by task 6696 on cpu 0: > compaction_deferred mm/compaction.c:150 [inline] > try_to_compact_pages+0x207/0x940 mm/compaction.c:2838 > __alloc_pages_direct_compact+0x65/0x1d0 mm/page_alloc.c:4066 > __alloc_pages_slowpath+0x360/0x5f0 mm/page_alloc.c:4787 > __alloc_frozen_pages_noprof+0x270/0x360 mm/page_alloc.c:5161 > alloc_pages_mpol+0xb3/0x250 mm/mempolicy.c:2416 > alloc_frozen_pages_noprof+0x90/0x110 mm/mempolicy.c:2487 > ___kmalloc_large_node+0x52/0x100 mm/slub.c:4317 > __kmalloc_large_node_noprof+0x16/0xa0 mm/slub.c:4348 > __do_kmalloc_node mm/slub.c:4364 [inline] > __kmalloc_noprof+0x2ab/0x3e0 mm/slub.c:4388 > kmalloc_noprof include/linux/slab.h:909 [inline] > kmalloc_array_noprof include/linux/slab.h:948 [inline] > io_vec_realloc io_uring/rsrc.c:1327 [inline] > io_import_reg_vec+0x645/0xe80 io_uring/rsrc.c:1520 > io_sendmsg_zc+0x91/0x550 io_uring/net.c:1545 > __io_issue_sqe+0xfb/0x2e0 io_uring/io_uring.c:1771 > io_issue_sqe+0x53/0x970 io_uring/io_uring.c:1794 > io_queue_sqe io_uring/io_uring.c:2023 [inline] > io_submit_sqe io_uring/io_uring.c:2283 [inline] > io_submit_sqes+0x675/0x1060 io_uring/io_uring.c:2396 > __do_sys_io_uring_enter io_uring/io_uring.c:3463 [inline] > __se_sys_io_uring_enter+0x1c1/0x1b70 io_uring/io_uring.c:3397 > __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3397 > x64_sys_call+0x2de1/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:427 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > value changed: 0x00000005 -> 0x00000004 > > Reported by Kernel Concurrency Sanitizer on: > CPU: 0 UID: 0 PID: 6696 Comm: syz.2.1234 Not tainted syzkaller #0 PREEMPT(voluntary) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 > ================================================================== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > If the report is already addressed, let syzbot know by replying with: > #syz fix: exact-commit-title > > If you want to overwrite report's subsystems, reply with: > #syz set subsystems: new-subsystem > (See the list of subsystem names on the web dashboard) > > If the report is a duplicate of another one, reply with: > #syz dup: exact-subject-of-another-report > > If you want to undo deduplication, reply with: > #syz undup