https://bugzilla.kernel.org/show_bug.cgi?id=205567 Bug ID: 205567 Summary: potential (possibly benign) data race on ext4_dir_entry_2->inode when getdents64 and rename happens on the same directory Product: File System Version: 2.5 Kernel Version: 5.4-rc5 Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: ext4 Assignee: fs_ext4@xxxxxxxxxxxxxxxxxxxx Reporter: mengxu.gatech@xxxxxxxxx Regression: No I am reporting a potential data race (maybe benign) in the ext4 layer on ext4_dir_entry_2->inode when getdents64 and rename happens on the same directory. [Setup] mkdir(dir_foo, 0777); open(dir_foo, 0x10000, 0777) = 0; dup2(0, 199) = 199; [Thread 1] getdents64(199, <some buffer>, 4469) = 48; [Thread 2] rename(dir_foo, aaaaa) = 0; The function call trace is shown below: [Thread 1: SYS_getdents64] __do_sys_getdents64 ksys_getdents64 iterate_dir ext4_readdir ext4_dx_readdir ext4_htree_fill_tree htree_dirblock_to_tree [READ] if (de->inode == 0) [Thread 2: SYS_rename] __do_renameat2 do_renameat2 vfs_rename ext4_rename2 ext4_rename ext4_rename_dir_finish [WRITE] ent->parent_de->inode = cpu_to_le32(dir_ino); I could confirm that the WRITE may happen before and after the READ operation by controlling the timing of the two threads, i.e., by setting breakpoints before the WRITE statement. However, I am not very sure about the implication of such a data race (e.g., causing violations of assumptions). I would appreciate if you could help check on this potential bug and advise whether this is a harmful data race or it is intended. Thank you! -- You are receiving this mail because: You are watching the assignee of the bug.
