e0f76ad130
The following Oops may be encountered if the device is reset, i.e. EEH recovery, while there is heavy I/O traffic: 59:mon> t [c000200db64bb680] c008000009264c40 cxlflash_queuecommand+0x3b8/0x500 [cxlflash] [c000200db64bb770] c00000000090d3b0 scsi_dispatch_cmd+0x130/0x2f0 [c000200db64bb7f0] c00000000090fdd8 scsi_request_fn+0x3c8/0x8d0 [c000200db64bb900] c00000000067f528 __blk_run_queue+0x68/0xb0 [c000200db64bb930] c00000000067ab80 __elv_add_request+0x140/0x3c0 [c000200db64bb9b0] c00000000068daac blk_execute_rq_nowait+0xec/0x1a0 [c000200db64bba00] c00000000068dbb0 blk_execute_rq+0x50/0xe0 [c000200db64bba50] c0000000006b2040 sg_io+0x1f0/0x520 [c000200db64bbaf0] c0000000006b2e94 scsi_cmd_ioctl+0x534/0x610 [c000200db64bbc20] c000000000926208 sd_ioctl+0x118/0x280 [c000200db64bbcc0] c00000000069f7ac blkdev_ioctl+0x7fc/0xe30 [c000200db64bbd20] c000000000439204 block_ioctl+0x84/0xa0 [c000200db64bbd40] c0000000003f8514 do_vfs_ioctl+0xd4/0xa00 [c000200db64bbde0] c0000000003f8f04 SyS_ioctl+0xc4/0x130 [c000200db64bbe30] c00000000000b184 system_call+0x58/0x6c When there is no room to send the I/O request, the cached room is refreshed by reading the memory mapped command room value from the AFU. The AFU register mapping is refreshed during a reset, creating a race condition that can lead to the Oops above. During a device reset, the AFU should not be unmapped until all the active send threads quiesce. An atomic counter, cmds_active, is currently used to track internal AFU commands and quiesce during reset. This same counter can also be used for the active send threads. Signed-off-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com> Acked-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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.