mainlining shenanigans
b9156daeb1
When the user issues a command with side effects, we will end up freezing the namespace request queue when updating disk info (and the same for the corresponding mpath disk node). However, we are not freezing the mpath node request queue, which means that mpath I/O can still come in and block on blk_queue_enter (called from nvme_ns_head_make_request -> direct_make_request). This is a deadlock, because blk_queue_enter will block until the inner namespace request queue is unfroze, but that process is blocked because the namespace revalidation is trying to update the mpath disk info and freeze its request queue (which will never complete because of the I/O that is blocked on blk_queue_enter). Fix this by freezing all the subsystem nsheads request queues before executing the passthru command. Given that these commands are infrequent we should not worry about this temporary I/O freeze to keep things sane. Here is the matching hang traces: -- [ 374.465002] INFO: task systemd-udevd:17994 blocked for more than 122 seconds. [ 374.472975] Not tainted 5.2.0-rc3-mpdebug+ #42 [ 374.478522] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 374.487274] systemd-udevd D 0 17994 1 0x00000000 [ 374.493407] Call Trace: [ 374.496145] __schedule+0x2ef/0x620 [ 374.500047] schedule+0x38/0xa0 [ 374.503569] blk_queue_enter+0x139/0x220 [ 374.507959] ? remove_wait_queue+0x60/0x60 [ 374.512540] direct_make_request+0x60/0x130 [ 374.517219] nvme_ns_head_make_request+0x11d/0x420 [nvme_core] [ 374.523740] ? generic_make_request_checks+0x307/0x6f0 [ 374.529484] generic_make_request+0x10d/0x2e0 [ 374.534356] submit_bio+0x75/0x140 [ 374.538163] ? guard_bio_eod+0x32/0xe0 [ 374.542361] submit_bh_wbc+0x171/0x1b0 [ 374.546553] block_read_full_page+0x1ed/0x330 [ 374.551426] ? check_disk_change+0x70/0x70 [ 374.556008] ? scan_shadow_nodes+0x30/0x30 [ 374.560588] blkdev_readpage+0x18/0x20 [ 374.564783] do_read_cache_page+0x301/0x860 [ 374.569463] ? blkdev_writepages+0x10/0x10 [ 374.574037] ? prep_new_page+0x88/0x130 [ 374.578329] ? get_page_from_freelist+0xa2f/0x1280 [ 374.583688] ? __alloc_pages_nodemask+0x179/0x320 [ 374.588947] read_cache_page+0x12/0x20 [ 374.593142] read_dev_sector+0x2d/0xd0 [ 374.597337] read_lba+0x104/0x1f0 [ 374.601046] find_valid_gpt+0xfa/0x720 [ 374.605243] ? string_nocheck+0x58/0x70 [ 374.609534] ? find_valid_gpt+0x720/0x720 [ 374.614016] efi_partition+0x89/0x430 [ 374.618113] ? string+0x48/0x60 [ 374.621632] ? snprintf+0x49/0x70 [ 374.625339] ? find_valid_gpt+0x720/0x720 [ 374.629828] check_partition+0x116/0x210 [ 374.634214] rescan_partitions+0xb6/0x360 [ 374.638699] __blkdev_reread_part+0x64/0x70 [ 374.643377] blkdev_reread_part+0x23/0x40 [ 374.647860] blkdev_ioctl+0x48c/0x990 [ 374.651956] block_ioctl+0x41/0x50 [ 374.655766] do_vfs_ioctl+0xa7/0x600 [ 374.659766] ? locks_lock_inode_wait+0xb1/0x150 [ 374.664832] ksys_ioctl+0x67/0x90 [ 374.668539] __x64_sys_ioctl+0x1a/0x20 [ 374.672732] do_syscall_64+0x5a/0x1c0 [ 374.676828] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 374.738474] INFO: task nvmeadm:49141 blocked for more than 123 seconds. [ 374.745871] Not tainted 5.2.0-rc3-mpdebug+ #42 [ 374.751419] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 374.760170] nvmeadm D 0 49141 36333 0x00004080 [ 374.766301] Call Trace: [ 374.769038] __schedule+0x2ef/0x620 [ 374.772939] schedule+0x38/0xa0 [ 374.776452] blk_mq_freeze_queue_wait+0x59/0x100 [ 374.781614] ? remove_wait_queue+0x60/0x60 [ 374.786192] blk_mq_freeze_queue+0x1a/0x20 [ 374.790773] nvme_update_disk_info.isra.57+0x5f/0x350 [nvme_core] [ 374.797582] ? nvme_identify_ns.isra.50+0x71/0xc0 [nvme_core] [ 374.804006] __nvme_revalidate_disk+0xe5/0x110 [nvme_core] [ 374.810139] nvme_revalidate_disk+0xa6/0x120 [nvme_core] [ 374.816078] ? nvme_submit_user_cmd+0x11e/0x320 [nvme_core] [ 374.822299] nvme_user_cmd+0x264/0x370 [nvme_core] [ 374.827661] nvme_dev_ioctl+0x112/0x1d0 [nvme_core] [ 374.833114] do_vfs_ioctl+0xa7/0x600 [ 374.837117] ? __audit_syscall_entry+0xdd/0x130 [ 374.842184] ksys_ioctl+0x67/0x90 [ 374.845891] __x64_sys_ioctl+0x1a/0x20 [ 374.850082] do_syscall_64+0x5a/0x1c0 [ 374.854178] entry_SYSCALL_64_after_hwframe+0x44/0xa9 -- Reported-by: James Puthukattukaran <james.puthukattukaran@oracle.com> Tested-by: James Puthukattukaran <james.puthukattukaran@oracle.com> Reviewed-by: Keith Busch <kbusch@kernel.org> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
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| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| README | ||
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.