On 2/2/23 00:52, David Howells wrote:
Hi John, David, Could you have a look at this?
Sure. So far, I have reproduced a crash using your simplified test program (it required three simulaneous running copies), and will look deeper now. In case it illuminates anything, the crash looked like this (below), and was obtained *without* setting KASAN. Also a minor point: this is from a git branch of the last commit in the series (commit fd20d0c1852e "block: convert bio_map_user_iov to use iov_iter_extract_pages"), rather than from top of linux-next. Kernel panic - not syncing: corrupted stack end detected inside scheduler CPU: 2 PID: 27177 Comm: syzbot_howells Not tainted 6.2.0-rc5-hubbard-github+ #3 Hardware name: ASUS X299-A/PRIME X299-A, BIOS 1503 08/03/2018 Call Trace: <TASK> dump_stack_lvl+0x4c/0x63 panic+0x113/0x2c4 ? folio_wait_bit_common+0xf6/0x360 __schedule+0xd1b/0xd20 schedule+0x5d/0xe0 io_schedule+0x42/0x70 folio_wait_bit_common+0x123/0x360 ? __pfx_wake_page_function+0x10/0x10 folio_wait_writeback+0x24/0x100 __filemap_fdatawait_range+0x7a/0x120 ? filemap_fdatawrite_wbc+0x69/0x80 ? __filemap_fdatawrite_range+0x58/0x80 filemap_write_and_wait_range+0x84/0xb0 __iomap_dio_rw+0x183/0x830 ? __lock_acquire+0x3b4/0x2620 iomap_dio_rw+0xe/0x40 ext4_file_read_iter+0x141/0x1c0 generic_file_splice_read+0x90/0x160 splice_direct_to_actor+0xb1/0x210 ? __pfx_direct_splice_actor+0x10/0x10 do_splice_direct+0x8c/0xd0 do_sendfile+0x352/0x600 do_syscall_64+0x37/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7f322d5116be Code: c3 0f 1f 00 4c 89 d2 4c 89 c6 e9 fd fd ff ff 0f 1f 44 00 00 31 c0 c3 0f 1f 44 00 00 f3 0f 1e fa 49 89 ca b8 28 00 00 00 0f 05 <48> 3d 01 f0 ff ff8 RSP: 002b:00007ffd8c914538 EFLAGS: 00000202 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007ffd8c914678 RCX: 00007f322d5116be RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000003 RBP: 0000000000000003 R08: 0000000000000001 R09: 00007f322d7f6740 R10: 000000000001dd00 R11: 0000000000000202 R12: 0000000000000000 R13: 00007ffd8c914690 R14: 0000558a11e29d78 R15: 00007f322d843020 </TASK> thanks, -- John Hubbard NVIDIA
