| Message ID | 20240924130053.107490-1-aha310510@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: migrate: annotate data-race in migrate_folio_unmap() | expand |
On 24.09.24 15:00, Jeongjun Park wrote: > I found a report from syzbot [1] > > This report shows that the value can be changed, but in reality, the > value of __folio_set_movable() cannot be changed because it holds the > folio refcount. > > Therefore, it is appropriate to add an annotate to make KCSAN > ignore that data-race. > > [1] > > ================================================================== > BUG: KCSAN: data-race in __filemap_remove_folio / migrate_pages_batch > > write to 0xffffea0004b81dd8 of 8 bytes by task 6348 on cpu 0: > page_cache_delete mm/filemap.c:153 [inline] > __filemap_remove_folio+0x1ac/0x2c0 mm/filemap.c:233 > filemap_remove_folio+0x6b/0x1f0 mm/filemap.c:265 > truncate_inode_folio+0x42/0x50 mm/truncate.c:178 > shmem_undo_range+0x25b/0xa70 mm/shmem.c:1028 > shmem_truncate_range mm/shmem.c:1144 [inline] > shmem_evict_inode+0x14d/0x530 mm/shmem.c:1272 > evict+0x2f0/0x580 fs/inode.c:731 > iput_final fs/inode.c:1883 [inline] > iput+0x42a/0x5b0 fs/inode.c:1909 > dentry_unlink_inode+0x24f/0x260 fs/dcache.c:412 > __dentry_kill+0x18b/0x4c0 fs/dcache.c:615 > dput+0x5c/0xd0 fs/dcache.c:857 > __fput+0x3fb/0x6d0 fs/file_table.c:439 > ____fput+0x1c/0x30 fs/file_table.c:459 > task_work_run+0x13a/0x1a0 kernel/task_work.c:228 > resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] > exit_to_user_mode_loop kernel/entry/common.c:114 [inline] > exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] > __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] > syscall_exit_to_user_mode+0xbe/0x130 kernel/entry/common.c:218 > do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > read to 0xffffea0004b81dd8 of 8 bytes by task 6342 on cpu 1: > __folio_test_movable include/linux/page-flags.h:699 [inline] > migrate_folio_unmap mm/migrate.c:1199 [inline] > migrate_pages_batch+0x24c/0x1940 mm/migrate.c:1797 > migrate_pages_sync mm/migrate.c:1963 [inline] > migrate_pages+0xff1/0x1820 mm/migrate.c:2072 > do_mbind mm/mempolicy.c:1390 [inline] > kernel_mbind mm/mempolicy.c:1533 [inline] > __do_sys_mbind mm/mempolicy.c:1607 [inline] > __se_sys_mbind+0xf76/0x1160 mm/mempolicy.c:1603 > __x64_sys_mbind+0x78/0x90 mm/mempolicy.c:1603 > x64_sys_call+0x2b4d/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:238 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > value changed: 0xffff888127601078 -> 0x0000000000000000 > > Reported-by: syzbot <syzkaller@googlegroups.com> > Cc: stable@vger.kernel.org Hmm, why stable? > Fixes: 7e2a5e5ab217 ("mm: migrate: use __folio_test_movable()") > Signed-off-by: Jeongjun Park <aha310510@gmail.com> > --- Acked-by: David Hildenbrand <david@redhat.com>
diff --git a/mm/migrate.c b/mm/migrate.c index 923ea80ba744..368ab3878fa6 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1118,7 +1118,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio, int rc = -EAGAIN; int old_page_state = 0; struct anon_vma *anon_vma = NULL; - bool is_lru = !__folio_test_movable(src); + bool is_lru = data_race(!__folio_test_movable(src)); bool locked = false; bool dst_locked = false;
I found a report from syzbot [1] This report shows that the value can be changed, but in reality, the value of __folio_set_movable() cannot be changed because it holds the folio refcount. Therefore, it is appropriate to add an annotate to make KCSAN ignore that data-race. [1] ================================================================== BUG: KCSAN: data-race in __filemap_remove_folio / migrate_pages_batch write to 0xffffea0004b81dd8 of 8 bytes by task 6348 on cpu 0: page_cache_delete mm/filemap.c:153 [inline] __filemap_remove_folio+0x1ac/0x2c0 mm/filemap.c:233 filemap_remove_folio+0x6b/0x1f0 mm/filemap.c:265 truncate_inode_folio+0x42/0x50 mm/truncate.c:178 shmem_undo_range+0x25b/0xa70 mm/shmem.c:1028 shmem_truncate_range mm/shmem.c:1144 [inline] shmem_evict_inode+0x14d/0x530 mm/shmem.c:1272 evict+0x2f0/0x580 fs/inode.c:731 iput_final fs/inode.c:1883 [inline] iput+0x42a/0x5b0 fs/inode.c:1909 dentry_unlink_inode+0x24f/0x260 fs/dcache.c:412 __dentry_kill+0x18b/0x4c0 fs/dcache.c:615 dput+0x5c/0xd0 fs/dcache.c:857 __fput+0x3fb/0x6d0 fs/file_table.c:439 ____fput+0x1c/0x30 fs/file_table.c:459 task_work_run+0x13a/0x1a0 kernel/task_work.c:228 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0xbe/0x130 kernel/entry/common.c:218 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffea0004b81dd8 of 8 bytes by task 6342 on cpu 1: __folio_test_movable include/linux/page-flags.h:699 [inline] migrate_folio_unmap mm/migrate.c:1199 [inline] migrate_pages_batch+0x24c/0x1940 mm/migrate.c:1797 migrate_pages_sync mm/migrate.c:1963 [inline] migrate_pages+0xff1/0x1820 mm/migrate.c:2072 do_mbind mm/mempolicy.c:1390 [inline] kernel_mbind mm/mempolicy.c:1533 [inline] __do_sys_mbind mm/mempolicy.c:1607 [inline] __se_sys_mbind+0xf76/0x1160 mm/mempolicy.c:1603 __x64_sys_mbind+0x78/0x90 mm/mempolicy.c:1603 x64_sys_call+0x2b4d/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:238 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0xffff888127601078 -> 0x0000000000000000 Reported-by: syzbot <syzkaller@googlegroups.com> Cc: stable@vger.kernel.org Fixes: 7e2a5e5ab217 ("mm: migrate: use __folio_test_movable()") Signed-off-by: Jeongjun Park <aha310510@gmail.com> --- mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --