syzbot

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BUG: KCSAN: data-race in page_cache_ra_unbounded / proc_task_name

write to 0xffff88803743802c of 4 bytes by task 32189 on cpu 1:
 memalloc_nofs_restore include/linux/sched/mm.h:258 [inline]
 page_cache_ra_unbounded+0x48c/0x4c0 mm/readahead.c:239
 ondemand_readahead+0x560/0x780 mm/readahead.c:267
 page_cache_sync_ra+0x18f/0x1a0 mm/readahead.c:577
 page_cache_sync_readahead include/linux/pagemap.h:839 [inline]
 generic_file_buffered_read_get_pages+0x234/0xaf0 mm/filemap.c:2365
 generic_file_buffered_read+0x26e/0x9c0 mm/filemap.c:2485
 generic_file_read_iter+0x82/0x3e0 mm/filemap.c:2637
 ext4_file_read_iter+0x2e0/0x430 fs/ext4/file.c:74
 __kernel_read+0x306/0x580 fs/read_write.c:454
 integrity_kernel_read+0x4c/0x70 security/integrity/iint.c:191
 ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:484 [inline]
 ima_calc_file_shash security/integrity/ima/ima_crypto.c:515 [inline]
 ima_calc_file_hash+0x929/0x1310 security/integrity/ima/ima_crypto.c:572
 ima_collect_measurement+0x168/0x310 security/integrity/ima/ima_api.c:250
 process_measurement+0xa4c/0x10c0 security/integrity/ima/ima_main.c:330
 ima_file_check+0x75/0xa0 security/integrity/ima/ima_main.c:498
 do_open fs/namei.c:3256 [inline]
 path_openat+0x188a/0x20a0 fs/namei.c:3371
 do_filp_open+0xbd/0x1d0 fs/namei.c:3398
 do_sys_openat2+0xa3/0x250 fs/open.c:1172
 do_sys_open fs/open.c:1188 [inline]
 __do_sys_open fs/open.c:1196 [inline]
 __se_sys_open fs/open.c:1192 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1192
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88803743802c of 4 bytes by task 4868 on cpu 0:
 proc_task_name+0x3b/0x1e0 fs/proc/array.c:106
 comm_show+0x45/0xd0 fs/proc/base.c:1697
 seq_read_iter+0x2ef/0x910 fs/seq_file.c:227
 seq_read+0x221/0x260 fs/seq_file.c:159
 vfs_read+0x154/0x5d0 fs/read_write.c:494
 ksys_read+0xce/0x180 fs/read_write.c:634
 __do_sys_read fs/read_write.c:644 [inline]
 __se_sys_read fs/read_write.c:642 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:642
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4868 Comm: systemd-journal Not tainted 5.11.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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