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024d515aab
commit 61cce6f6ee upstream.
When boxes are run near (or to) OOM, we have a problem with the discard
page allocation in sd. If we fail allocating the special page, we return
busy, and it'll get retried. But since ordering is honored for dispatch
requests, we can keep retrying this same IO and failing. Behind that IO
could be requests that want to free memory, but they never get the
chance. This means you get repeated spews of traces like this:
[1201401.625972] Call Trace:
[1201401.631748] dump_stack+0x4d/0x65
[1201401.639445] warn_alloc+0xec/0x190
[1201401.647335] __alloc_pages_slowpath+0xe84/0xf30
[1201401.657722] ? get_page_from_freelist+0x11b/0xb10
[1201401.668475] ? __alloc_pages_slowpath+0x2e/0xf30
[1201401.679054] __alloc_pages_nodemask+0x1f9/0x210
[1201401.689424] alloc_pages_current+0x8c/0x110
[1201401.699025] sd_setup_write_same16_cmnd+0x51/0x150
[1201401.709987] sd_init_command+0x49c/0xb70
[1201401.719029] scsi_setup_cmnd+0x9c/0x160
[1201401.727877] scsi_queue_rq+0x4d9/0x610
[1201401.736535] blk_mq_dispatch_rq_list+0x19a/0x360
[1201401.747113] blk_mq_sched_dispatch_requests+0xff/0x190
[1201401.758844] __blk_mq_run_hw_queue+0x95/0xa0
[1201401.768653] blk_mq_run_work_fn+0x2c/0x30
[1201401.777886] process_one_work+0x14b/0x400
[1201401.787119] worker_thread+0x4b/0x470
[1201401.795586] kthread+0x110/0x150
[1201401.803089] ? rescuer_thread+0x320/0x320
[1201401.812322] ? kthread_park+0x90/0x90
[1201401.820787] ? do_syscall_64+0x53/0x150
[1201401.829635] ret_from_fork+0x29/0x40
Ensure that the discard page allocation has a mempool backing, so we
know we can make progress.
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.