83e1226b0e
When destroying a queue, when calling sock_release, the network stack might need to allocate an skb to send a FIN/RST. When that happens during memory pressure, there is a need to reclaim memory, which in turn may ask the nvme-tcp device to write out dirty pages, however this is not possible due to a ctrl teardown that is going on. Set PF_MEMALLOC to the task that releases the socket to grant access to PF_MEMALLOC reserves. In addition, do the same for the nvme-tcp thread as this may also originate from the swap itself and should be more resilient to memory pressure situations. This fixes the following lockdep complaint: -- ====================================================== WARNING: possible circular locking dependency detected 6.0.0-rc2+ #25 Tainted: G W ------------------------------------------------------ kswapd0/92 is trying to acquire lock: ffff888114003240 (sk_lock-AF_INET-NVME){+.+.}-{0:0}, at: tcp_sendpage+0x23/0xa0 but task is already holding lock: ffffffff97e95ca0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x987/0x10d0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}-{0:0}: fs_reclaim_acquire+0x11e/0x160 kmem_cache_alloc_node+0x44/0x530 __alloc_skb+0x158/0x230 tcp_send_active_reset+0x7e/0x730 tcp_disconnect+0x1272/0x1ae0 __tcp_close+0x707/0xd90 tcp_close+0x26/0x80 inet_release+0xfa/0x220 sock_release+0x85/0x1a0 nvme_tcp_free_queue+0x1fd/0x470 [nvme_tcp] nvme_do_delete_ctrl+0x130/0x13d [nvme_core] nvme_sysfs_delete.cold+0x8/0xd [nvme_core] kernfs_fop_write_iter+0x356/0x530 vfs_write+0x4e8/0xce0 ksys_write+0xfd/0x1d0 do_syscall_64+0x58/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #0 (sk_lock-AF_INET-NVME){+.+.}-{0:0}: __lock_acquire+0x2a0c/0x5690 lock_acquire+0x18e/0x4f0 lock_sock_nested+0x37/0xc0 tcp_sendpage+0x23/0xa0 inet_sendpage+0xad/0x120 kernel_sendpage+0x156/0x440 nvme_tcp_try_send+0x48a/0x2630 [nvme_tcp] nvme_tcp_queue_rq+0xefb/0x17e0 [nvme_tcp] __blk_mq_try_issue_directly+0x452/0x660 blk_mq_plug_issue_direct.constprop.0+0x207/0x700 blk_mq_flush_plug_list+0x6f5/0xc70 __blk_flush_plug+0x264/0x410 blk_finish_plug+0x4b/0xa0 shrink_lruvec+0x1263/0x1ea0 shrink_node+0x736/0x1a80 balance_pgdat+0x740/0x10d0 kswapd+0x5f2/0xaf0 kthread+0x256/0x2f0 ret_from_fork+0x1f/0x30 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(sk_lock-AF_INET-NVME); lock(fs_reclaim); lock(sk_lock-AF_INET-NVME); *** DEADLOCK *** 3 locks held by kswapd0/92: #0: ffffffff97e95ca0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x987/0x10d0 #1: ffff88811f21b0b0 (q->srcu){....}-{0:0}, at: blk_mq_flush_plug_list+0x6b3/0xc70 #2: ffff888170b11470 (&queue->send_mutex){+.+.}-{3:3}, at: nvme_tcp_queue_rq+0xeb9/0x17e0 [nvme_tcp] Fixes: 3f2304f8c6d6 ("nvme-tcp: add NVMe over TCP host driver") Reported-by: Daniel Wagner <dwagner@suse.de> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Tested-by: Daniel Wagner <dwagner@suse.de> Signed-off-by: Christoph Hellwig <hch@lst.de>
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.