[moderation] [block?] KCSAN: data-race in __dd_dispatch_request / ll_back_merge_fn

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c527f5606aa5 Merge tag 'powerpc-6.7-4' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1670dcf4e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=ac34c1f29a8029df
dashboard link: https://syzkaller.appspot.com/bug?extid=71239ed0900c34222fc0
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [ax...@kernel.dk linux...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/92e0da74d3d8/disk-c527f560.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/72753f3c654e/vmlinux-c527f560.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d335b5d505d2/bzImage-c527f560.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+71239e...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __dd_dispatch_request / ll_back_merge_fn

write to 0xffff88810181dc80 of 8 bytes by task 11033 on cpu 0:
deadline_remove_request block/mq-deadline.c:224 [inline]
deadline_move_request block/mq-deadline.c:286 [inline]
__dd_dispatch_request+0x606/0x6c0 block/mq-deadline.c:546
dd_dispatch_request+0x1d4/0x2c0 block/mq-deadline.c:613
__blk_mq_do_dispatch_sched block/blk-mq-sched.c:118 [inline]
blk_mq_do_dispatch_sched block/blk-mq-sched.c:184 [inline]
__blk_mq_sched_dispatch_requests+0x3ed/0xd20 block/blk-mq-sched.c:309
blk_mq_sched_dispatch_requests+0x99/0x100 block/blk-mq-sched.c:333
blk_mq_run_hw_queue+0x2a4/0x4c0 block/blk-mq.c:2264
blk_mq_flush_plug_list+0x7b6/0xdc0 block/blk-mq.c:2812
__blk_flush_plug+0x210/0x260 block/blk-core.c:1150
blk_finish_plug+0x47/0x60 block/blk-core.c:1174
__iomap_dio_rw+0xc69/0x1090 fs/iomap/direct-io.c:667
iomap_dio_rw+0x40/0x90 fs/iomap/direct-io.c:748
ext4_dio_read_iter fs/ext4/file.c:94 [inline]
ext4_file_read_iter+0x21c/0x2a0 fs/ext4/file.c:145
call_read_iter include/linux/fs.h:2014 [inline]
copy_splice_read+0x26b/0x4b0 fs/splice.c:364
vfs_splice_read fs/splice.c:992 [inline]
splice_direct_to_actor+0x2aa/0x690 fs/splice.c:1069
do_splice_direct+0x10d/0x190 fs/splice.c:1194
do_sendfile+0x3c4/0x980 fs/read_write.c:1254
__do_sys_sendfile64 fs/read_write.c:1322 [inline]
__se_sys_sendfile64 fs/read_write.c:1308 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88810181dc80 of 8 bytes by task 11031 on cpu 1:
req_set_nomerge block/blk.h:351 [inline]
ll_back_merge_fn+0x29c/0x4a0 block/blk-merge.c:647
bio_attempt_back_merge+0x58/0x500 block/blk-merge.c:982
blk_attempt_bio_merge+0x43d/0x480 block/blk-merge.c:1068
blk_attempt_plug_merge+0xb4/0xf0 block/blk-merge.c:1115
blk_mq_attempt_bio_merge block/blk-mq.c:2853 [inline]
blk_mq_get_new_requests block/blk-mq.c:2873 [inline]
blk_mq_submit_bio+0x3ab/0xd90 block/blk-mq.c:2982
__submit_bio+0x11c/0x350 block/blk-core.c:607
__submit_bio_noacct_mq block/blk-core.c:686 [inline]
submit_bio_noacct_nocheck+0x449/0x5e0 block/blk-core.c:715
submit_bio_noacct+0x70c/0x8c0 block/blk-core.c:809
submit_bio+0xb7/0xc0 block/blk-core.c:842
swap_writepage_bdev_async mm/page_io.c:368 [inline]
__swap_writepage+0x69d/0xdb0 mm/page_io.c:386
swap_writepage+0x6e/0x120 mm/page_io.c:204
shmem_writepage+0x7a6/0x970 mm/shmem.c:1500
pageout mm/vmscan.c:654 [inline]
shrink_folio_list+0x1952/0x2540 mm/vmscan.c:1315
shrink_inactive_list mm/vmscan.c:1913 [inline]
shrink_list mm/vmscan.c:2154 [inline]
shrink_lruvec+0xd80/0x17a0 mm/vmscan.c:5626
shrink_node_memcgs mm/vmscan.c:5812 [inline]
shrink_node+0xab3/0x15c0 mm/vmscan.c:5847
shrink_zones mm/vmscan.c:6086 [inline]
do_try_to_free_pages+0x43d/0xce0 mm/vmscan.c:6148
try_to_free_mem_cgroup_pages+0x1e2/0x480 mm/vmscan.c:6463
try_charge_memcg+0x280/0xd30 mm/memcontrol.c:2742
obj_cgroup_charge_pages+0xab/0x130 mm/memcontrol.c:3255
__memcg_kmem_charge_page+0x9c/0x170 mm/memcontrol.c:3281
__alloc_pages+0x1bb/0x340 mm/page_alloc.c:4585
alloc_pages_mpol+0xb1/0x1d0 mm/mempolicy.c:2133
alloc_pages+0xe0/0x100 mm/mempolicy.c:2204
vm_area_alloc_pages mm/vmalloc.c:3063 [inline]
__vmalloc_area_node mm/vmalloc.c:3139 [inline]
__vmalloc_node_range+0x6d2/0xea0 mm/vmalloc.c:3320
kvmalloc_node+0x121/0x160 mm/util.c:642
kvmalloc include/linux/slab.h:738 [inline]
xt_alloc_table_info+0x3d/0x80 net/netfilter/x_tables.c:1192
do_replace net/ipv4/netfilter/arp_tables.c:970 [inline]
do_arpt_set_ctl+0x634/0x13b0 net/ipv4/netfilter/arp_tables.c:1421
nf_setsockopt+0x18d/0x1b0 net/netfilter/nf_sockopt.c:101
ip_setsockopt+0xe6/0x100 net/ipv4/ip_sockglue.c:1426
tcp_setsockopt+0x90/0xa0 net/ipv4/tcp.c:3724
sock_common_setsockopt+0x61/0x70 net/core/sock.c:3711
do_sock_setsockopt net/socket.c:2311 [inline]
__sys_setsockopt+0x1d4/0x240 net/socket.c:2334
__do_sys_setsockopt net/socket.c:2343 [inline]
__se_sys_setsockopt net/socket.c:2340 [inline]
__x64_sys_setsockopt+0x66/0x80 net/socket.c:2340
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0xffff888101888340 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11031 Comm: syz-executor.1 Not tainted 6.7.0-rc4-syzkaller-00424-gc527f5606aa5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================
syz-executor.1 (11031) used greatest stack depth: 8056 bytes left


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.