6772387e82
commit 28936b62e71e41600bab319f262ea9f9b1027629 upstream. inode->i_blocks could be accessed concurrently as noticed by KCSAN, BUG: KCSAN: data-race in ext4_do_update_inode [ext4] / inode_add_bytes write to 0xffff9a00d4b982d0 of 8 bytes by task 22100 on cpu 118: inode_add_bytes+0x65/0xf0 __inode_add_bytes at fs/stat.c:689 (inlined by) inode_add_bytes at fs/stat.c:702 ext4_mb_new_blocks+0x418/0xca0 [ext4] ext4_ext_map_blocks+0x1a6b/0x27b0 [ext4] ext4_map_blocks+0x1a9/0x950 [ext4] _ext4_get_block+0xfc/0x270 [ext4] ext4_get_block_unwritten+0x33/0x50 [ext4] __block_write_begin_int+0x22e/0xae0 __block_write_begin+0x39/0x50 ext4_write_begin+0x388/0xb50 [ext4] ext4_da_write_begin+0x35f/0x8f0 [ext4] generic_perform_write+0x15d/0x290 ext4_buffered_write_iter+0x11f/0x210 [ext4] ext4_file_write_iter+0xce/0x9e0 [ext4] new_sync_write+0x29c/0x3b0 __vfs_write+0x92/0xa0 vfs_write+0x103/0x260 ksys_write+0x9d/0x130 __x64_sys_write+0x4c/0x60 do_syscall_64+0x91/0xb05 entry_SYSCALL_64_after_hwframe+0x49/0xbe read to 0xffff9a00d4b982d0 of 8 bytes by task 8 on cpu 65: ext4_do_update_inode+0x4a0/0xf60 [ext4] ext4_inode_blocks_set at fs/ext4/inode.c:4815 ext4_mark_iloc_dirty+0xaf/0x160 [ext4] ext4_mark_inode_dirty+0x129/0x3e0 [ext4] ext4_convert_unwritten_extents+0x253/0x2d0 [ext4] ext4_convert_unwritten_io_end_vec+0xc5/0x150 [ext4] ext4_end_io_rsv_work+0x22c/0x350 [ext4] process_one_work+0x54f/0xb90 worker_thread+0x80/0x5f0 kthread+0x1cd/0x1f0 ret_from_fork+0x27/0x50 4 locks held by kworker/u256:0/8: #0: ffff9a025abc4328 ((wq_completion)ext4-rsv-conversion){+.+.}, at: process_one_work+0x443/0xb90 #1: ffffab5a862dbe20 ((work_completion)(&ei->i_rsv_conversion_work)){+.+.}, at: process_one_work+0x443/0xb90 #2: ffff9a025a9d0f58 (jbd2_handle){++++}, at: start_this_handle+0x1c1/0x9d0 [jbd2] #3: ffff9a00d4b985d8 (&(&ei->i_raw_lock)->rlock){+.+.}, at: ext4_do_update_inode+0xaa/0xf60 [ext4] irq event stamp: 3009267 hardirqs last enabled at (3009267): [<ffffffff980da9b7>] __find_get_block+0x107/0x790 hardirqs last disabled at (3009266): [<ffffffff980da8f9>] __find_get_block+0x49/0x790 softirqs last enabled at (3009230): [<ffffffff98a0034c>] __do_softirq+0x34c/0x57c softirqs last disabled at (3009223): [<ffffffff97cc67a2>] irq_exit+0xa2/0xc0 Reported by Kernel Concurrency Sanitizer on: CPU: 65 PID: 8 Comm: kworker/u256:0 Tainted: G L 5.6.0-rc2-next-20200221+ #7 Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019 Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work [ext4] The plain read is outside of inode->i_lock critical section which results in a data race. Fix it by adding READ_ONCE() there. Link: https://lore.kernel.org/r/20200222043258.2279-1-cai@lca.pw Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.