search for: filemap_fault

On Thu, Aug 10, 2017 at 05:40:34PM +0100, Richard W.M. Jones wrote: > If using indirect descriptors, you can make the total_sg as large as > you want. That would be a spec violation though, even if it happens to work on current QEMU. The spec says: A driver MUST NOT create a descriptor chain longer than the Queue Size of the device. What prompted this patch? Do we ever encounter this

On Thu, Aug 10, 2017 at 05:40:34PM +0100, Richard W.M. Jones wrote: > If using indirect descriptors, you can make the total_sg as large as > you want. That would be a spec violation though, even if it happens to work on current QEMU. The spec says: A driver MUST NOT create a descriptor chain longer than the Queue Size of the device. What prompted this patch? Do we ever encounter this

...g.cgi?id=6672 A file in btrfs is mmaped and the mmaped buffer is passed to pwrite to write to the same page of the same file. In btrfs_file_aio_write(), the pages is locked by prepare_pages(). So when btrfs_copy_from_user() is called, page fault happens and the same page needs to be locked again in filemap_fault(). The fix is to move iov_iter_fault_in_readable() before prepage_pages() to make page fault happen before pages are locked. And also disable page fault in critical region in btrfs_copy_from_user(). Signed-off-by: Xin Zhong <xin.zhong@intel.com> --- fs/btrfs/file.c | 23 +++++-------------...

...2] blk_mq_run_hw_queue+0x14/0x20 [ 4.054485] blk_mq_sched_insert_requests+0x96/0x120 [ 4.055095] blk_mq_flush_plug_list+0x19d/0x410 [ 4.055661] blk_flush_plug_list+0xf9/0x2b0 [ 4.056182] blk_finish_plug+0x2c/0x40 [ 4.056655] __do_page_cache_readahead+0x32e/0x400 [ 4.057261] filemap_fault+0x2fb/0x890 [ 4.057731] ? filemap_fault+0x2fb/0x890 [ 4.058220] ? find_held_lock+0x3c/0xb0 [ 4.058714] ext4_filemap_fault+0x34/0x50 [ 4.059212] __do_fault+0x1e/0x110 [ 4.059644] __handle_mm_fault+0x6b2/0x1080 [ 4.060167] handle_mm_fault+0x178/0x350 [ 4.060662] __do_page_...

...x20 > [ 4.054485] blk_mq_sched_insert_requests+0x96/0x120 > [ 4.055095] blk_mq_flush_plug_list+0x19d/0x410 > [ 4.055661] blk_flush_plug_list+0xf9/0x2b0 > [ 4.056182] blk_finish_plug+0x2c/0x40 > [ 4.056655] __do_page_cache_readahead+0x32e/0x400 > [ 4.057261] filemap_fault+0x2fb/0x890 > [ 4.057731] ? filemap_fault+0x2fb/0x890 > [ 4.058220] ? find_held_lock+0x3c/0xb0 > [ 4.058714] ext4_filemap_fault+0x34/0x50 > [ 4.059212] __do_fault+0x1e/0x110 > [ 4.059644] __handle_mm_fault+0x6b2/0x1080 > [ 4.060167] handle_mm_fault+0x178/0x...

...x20 > [ 4.054485] blk_mq_sched_insert_requests+0x96/0x120 > [ 4.055095] blk_mq_flush_plug_list+0x19d/0x410 > [ 4.055661] blk_flush_plug_list+0xf9/0x2b0 > [ 4.056182] blk_finish_plug+0x2c/0x40 > [ 4.056655] __do_page_cache_readahead+0x32e/0x400 > [ 4.057261] filemap_fault+0x2fb/0x890 > [ 4.057731] ? filemap_fault+0x2fb/0x890 > [ 4.058220] ? find_held_lock+0x3c/0xb0 > [ 4.058714] ext4_filemap_fault+0x34/0x50 > [ 4.059212] __do_fault+0x1e/0x110 > [ 4.059644] __handle_mm_fault+0x6b2/0x1080 > [ 4.060167] handle_mm_fault+0x178/0x...

...8.341630] dump_header+0x61/0x5ea [ 238.341942] oom_kill_process.cold+0xb/0x10 [ 238.342299] out_of_memory+0x24d/0x5a0 [ 238.342625] __alloc_pages_slowpath+0xd12/0x1020 [ 238.343024] __alloc_pages_nodemask+0x391/0x410 [ 238.343407] pagecache_get_page+0xc3/0x3a0 [ 238.343757] filemap_fault+0x804/0xc30 [ 238.344083] ? ext4_filemap_fault+0x28/0x42 [ 238.344444] ext4_filemap_fault+0x30/0x42 [ 238.344789] __do_fault+0x37/0x1a0 [ 238.345087] __handle_mm_fault+0x104d/0x1ab0 [ 238.345450] handle_mm_fault+0x169/0x360 [ 238.345790] do_user_addr_fault+0x20d/0x490 [ 2...

...8.341630] dump_header+0x61/0x5ea [ 238.341942] oom_kill_process.cold+0xb/0x10 [ 238.342299] out_of_memory+0x24d/0x5a0 [ 238.342625] __alloc_pages_slowpath+0xd12/0x1020 [ 238.343024] __alloc_pages_nodemask+0x391/0x410 [ 238.343407] pagecache_get_page+0xc3/0x3a0 [ 238.343757] filemap_fault+0x804/0xc30 [ 238.344083] ? ext4_filemap_fault+0x28/0x42 [ 238.344444] ext4_filemap_fault+0x30/0x42 [ 238.344789] __do_fault+0x37/0x1a0 [ 238.345087] __handle_mm_fault+0x104d/0x1ab0 [ 238.345450] handle_mm_fault+0x169/0x360 [ 238.345790] do_user_addr_fault+0x20d/0x490 [ 2...

...8.341630] dump_header+0x61/0x5ea [ 238.341942] oom_kill_process.cold+0xb/0x10 [ 238.342299] out_of_memory+0x24d/0x5a0 [ 238.342625] __alloc_pages_slowpath+0xd12/0x1020 [ 238.343024] __alloc_pages_nodemask+0x391/0x410 [ 238.343407] pagecache_get_page+0xc3/0x3a0 [ 238.343757] filemap_fault+0x804/0xc30 [ 238.344083] ? ext4_filemap_fault+0x28/0x42 [ 238.344444] ext4_filemap_fault+0x30/0x42 [ 238.344789] __do_fault+0x37/0x1a0 [ 238.345087] __handle_mm_fault+0x104d/0x1ab0 [ 238.345450] handle_mm_fault+0x169/0x360 [ 238.345790] do_user_addr_fault+0x20d/0x490 [ 2...

...8.341630] dump_header+0x61/0x5ea [ 238.341942] oom_kill_process.cold+0xb/0x10 [ 238.342299] out_of_memory+0x24d/0x5a0 [ 238.342625] __alloc_pages_slowpath+0xd12/0x1020 [ 238.343024] __alloc_pages_nodemask+0x391/0x410 [ 238.343407] pagecache_get_page+0xc3/0x3a0 [ 238.343757] filemap_fault+0x804/0xc30 [ 238.344083] ? ext4_filemap_fault+0x28/0x42 [ 238.344444] ext4_filemap_fault+0x30/0x42 [ 238.344789] __do_fault+0x37/0x1a0 [ 238.345087] __handle_mm_fault+0x104d/0x1ab0 [ 238.345450] handle_mm_fault+0x169/0x360 [ 238.345790] do_user_addr_fault+0x20d/0x490 [ 2...

...8.341630] dump_header+0x61/0x5ea [ 238.341942] oom_kill_process.cold+0xb/0x10 [ 238.342299] out_of_memory+0x24d/0x5a0 [ 238.342625] __alloc_pages_slowpath+0xd12/0x1020 [ 238.343024] __alloc_pages_nodemask+0x391/0x410 [ 238.343407] pagecache_get_page+0xc3/0x3a0 [ 238.343757] filemap_fault+0x804/0xc30 [ 238.344083] ? ext4_filemap_fault+0x28/0x42 [ 238.344444] ext4_filemap_fault+0x30/0x42 [ 238.344789] __do_fault+0x37/0x1a0 [ 238.345087] __handle_mm_fault+0x104d/0x1ab0 [ 238.345450] handle_mm_fault+0x169/0x360 [ 238.345790] do_user_addr_fault+0x20d/0x490 [ 2...

...oom_kill_process.cold+0xb/0x10 > > [ 238.342299] out_of_memory+0x24d/0x5a0 > > [ 238.342625] __alloc_pages_slowpath+0xd12/0x1020 > > [ 238.343024] __alloc_pages_nodemask+0x391/0x410 > > [ 238.343407] pagecache_get_page+0xc3/0x3a0 > > [ 238.343757] filemap_fault+0x804/0xc30 > > [ 238.344083] ? ext4_filemap_fault+0x28/0x42 > > [ 238.344444] ext4_filemap_fault+0x30/0x42 > > [ 238.344789] __do_fault+0x37/0x1a0 > > [ 238.345087] __handle_mm_fault+0x104d/0x1ab0 > > [ 238.345450] handle_mm_fault+0x169/0x360 >...

...10b536e>] ? filemap_write_and_wait+0x26/0x32 [ 240.595563] [<ffffffffa02c0d35>] ? nfs_setattr+0xb9/0x117 [nfs] [ 240.596670] [<ffffffff810b3a0b>] ? find_get_page+0x1a/0x77 [ 240.598012] [<ffffffff810b3bb9>] ? lock_page+0x9/0x1f [ 240.598878] [<ffffffff810b41ee>] ? filemap_fault+0xb9/0x2f6 [ 240.599839] [<ffffffff810ca3c2>] ? __do_fault+0x38c/0x3c3 [ 240.601003] [<ffffffff810ee1ce>] ? do_sync_write+0xce/0x113 [ 240.602082] [<ffffffff81051e75>] ? current_fs_time+0x1e/0x24 [ 240.602968] [<ffffffff811009b7>] ? notify_change+0x180/0x2c5 [ 240.6...

...10b536e>] ? filemap_write_and_wait+0x26/0x32 [ 240.595563] [<ffffffffa02c0d35>] ? nfs_setattr+0xb9/0x117 [nfs] [ 240.596670] [<ffffffff810b3a0b>] ? find_get_page+0x1a/0x77 [ 240.598012] [<ffffffff810b3bb9>] ? lock_page+0x9/0x1f [ 240.598878] [<ffffffff810b41ee>] ? filemap_fault+0xb9/0x2f6 [ 240.599839] [<ffffffff810ca3c2>] ? __do_fault+0x38c/0x3c3 [ 240.601003] [<ffffffff810ee1ce>] ? do_sync_write+0xce/0x113 [ 240.602082] [<ffffffff81051e75>] ? current_fs_time+0x1e/0x24 [ 240.602968] [<ffffffff811009b7>] ? notify_change+0x180/0x2c5 [ 240.6...

...fs_get_inode_info_unix+0x8b/0x1e0 [cifs] Dec 25 05:35:56 machine-hostname kernel: [<ffffffff811e8ba0>] ? complete_walk+0x60/0xe0 Dec 25 05:35:56 machine-hostname kernel: [<ffffffff811ed823>] ? path_lookupat+0x83/0x7a0 Dec 25 05:35:56 machine-hostname kernel: [<ffffffff8116b8f5>] ? filemap_fault+0x225/0x430 Dec 25 05:35:56 machine-hostname kernel: [<ffffffffa023ed4c>] ? xfs_iunlock+0x11c/0x130 [xfs] Dec 25 05:35:56 machine-hostname kernel: [<ffffffff811c1d95>] ? __kmalloc+0x55/0x230 Dec 25 05:35:56 machine-hostname kernel: [<ffffffffa041723e>] ? build_path_from_dentry+0xa...

...5ea > [ 238.341942] oom_kill_process.cold+0xb/0x10 > [ 238.342299] out_of_memory+0x24d/0x5a0 > [ 238.342625] __alloc_pages_slowpath+0xd12/0x1020 > [ 238.343024] __alloc_pages_nodemask+0x391/0x410 > [ 238.343407] pagecache_get_page+0xc3/0x3a0 > [ 238.343757] filemap_fault+0x804/0xc30 > [ 238.344083] ? ext4_filemap_fault+0x28/0x42 > [ 238.344444] ext4_filemap_fault+0x30/0x42 > [ 238.344789] __do_fault+0x37/0x1a0 > [ 238.345087] __handle_mm_fault+0x104d/0x1ab0 > [ 238.345450] handle_mm_fault+0x169/0x360 > [ 238.345790] do_user...

...5ea > [ 238.341942] oom_kill_process.cold+0xb/0x10 > [ 238.342299] out_of_memory+0x24d/0x5a0 > [ 238.342625] __alloc_pages_slowpath+0xd12/0x1020 > [ 238.343024] __alloc_pages_nodemask+0x391/0x410 > [ 238.343407] pagecache_get_page+0xc3/0x3a0 > [ 238.343757] filemap_fault+0x804/0xc30 > [ 238.344083] ? ext4_filemap_fault+0x28/0x42 > [ 238.344444] ext4_filemap_fault+0x30/0x42 > [ 238.344789] __do_fault+0x37/0x1a0 > [ 238.345087] __handle_mm_fault+0x104d/0x1ab0 > [ 238.345450] handle_mm_fault+0x169/0x360 > [ 238.345790] do_user...

...5ea > [ 238.341942] oom_kill_process.cold+0xb/0x10 > [ 238.342299] out_of_memory+0x24d/0x5a0 > [ 238.342625] __alloc_pages_slowpath+0xd12/0x1020 > [ 238.343024] __alloc_pages_nodemask+0x391/0x410 > [ 238.343407] pagecache_get_page+0xc3/0x3a0 > [ 238.343757] filemap_fault+0x804/0xc30 > [ 238.344083] ? ext4_filemap_fault+0x28/0x42 > [ 238.344444] ext4_filemap_fault+0x30/0x42 > [ 238.344789] __do_fault+0x37/0x1a0 > [ 238.345087] __handle_mm_fault+0x104d/0x1ab0 > [ 238.345450] handle_mm_fault+0x169/0x360 > [ 238.345790] do_user...

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 All, I believe that I can pretty reliably reproduce the BUG mentioned in the attached dmesg output. (This doesn''t mean that you can, but I''ll detail what I''ve done here.) [This BUG is the same one that I reported last night.] 1) Create a 2 GB dynamically expanding disk. 2) Attach it to a VirtualBox machine. 3) Start the

...8.341630] dump_header+0x61/0x5ea [ 238.341942] oom_kill_process.cold+0xb/0x10 [ 238.342299] out_of_memory+0x24d/0x5a0 [ 238.342625] __alloc_pages_slowpath+0xd12/0x1020 [ 238.343024] __alloc_pages_nodemask+0x391/0x410 [ 238.343407] pagecache_get_page+0xc3/0x3a0 [ 238.343757] filemap_fault+0x804/0xc30 [ 238.344083] ? ext4_filemap_fault+0x28/0x42 [ 238.344444] ext4_filemap_fault+0x30/0x42 [ 238.344789] __do_fault+0x37/0x1a0 [ 238.345087] __handle_mm_fault+0x104d/0x1ab0 [ 238.345450] handle_mm_fault+0x169/0x360 [ 238.345790] do_user_addr_fault+0x20d/0x490 [ 2...