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Max Gurtovoy 62f99b62e5 nvme-rdma: use dynamic dma mapping per command 
Commit 87fd125344 ("nvme-rdma: remove redundant reference between
ib_device and tagset") caused a kernel panic when disconnecting from an
inaccessible controller (disconnect during re-connection).

--
nvme nvme0: Removing ctrl: NQN "testnqn1"
nvme_rdma: nvme_rdma_exit_request: hctx 0 queue_idx 1
BUG: unable to handle kernel paging request at 0000000080000228
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
...
Call Trace:
 blk_mq_exit_hctx+0x5c/0xf0
 blk_mq_exit_queue+0xd4/0x100
 blk_cleanup_queue+0x9a/0xc0
 nvme_rdma_destroy_io_queues+0x52/0x60 [nvme_rdma]
 nvme_rdma_shutdown_ctrl+0x3e/0x80 [nvme_rdma]
 nvme_do_delete_ctrl+0x53/0x80 [nvme_core]
 nvme_sysfs_delete+0x45/0x60 [nvme_core]
 kernfs_fop_write+0x105/0x180
 vfs_write+0xad/0x1a0
 ksys_write+0x5a/0xd0
 do_syscall_64+0x55/0x110
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fa215417154
--

The reason for this crash is accessing an already freed ib_device for
performing dma_unmap during exit_request commands. The root cause for
that is that during re-connection all the queues are destroyed and
re-created (and the ib_device is reference counted by the queues and
freed as well) but the tagset stays alive and all the DMA mappings (that
we perform in init_request) kept in the request context. The original
commit fixed a different bug that was introduced during bonding (aka nic
teaming) tests that for some scenarios change the underlying ib_device
and caused memory leakage and possible segmentation fault. This commit
is a complementary commit that also changes the wrong DMA mappings that
were saved in the request context and making the request sqe dma
mappings dynamic with the command lifetime (i.e. mapped in .queue_rq and
unmapped in .complete). It also fixes the above crash of accessing freed
ib_device during destruction of the tagset.

Fixes: 87fd125344 ("nvme-rdma: remove redundant reference between ib_device and tagset")
Reported-by: Jim Harris <james.r.harris@intel.com>
Suggested-by: Sagi Grimberg <sagi@grimberg.me>
Tested-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
2019-06-06 09:53:19 -07:00
arch One more patch to remove io.h from clk-provider.h. We used to need this 2019-05-16 19:05:35 -07:00
block for-5.2/block-post-20190516 2019-05-16 19:08:15 -07:00
certs kexec, KEYS: Make use of platform keyring for signature verify 2019-02-04 17:34:07 -05:00
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2019-05-07 22:03:58 -07:00
Documentation Conversion of vendor-prefixes.txt to json-schema 2019-05-16 18:54:13 -07:00
drivers nvme-rdma: use dynamic dma mapping per command 2019-06-06 09:53:19 -07:00
fs for-linus-20190516 2019-05-16 19:10:37 -07:00
include for-5.2/block-post-20190516 2019-05-16 19:08:15 -07:00
init mm: shuffle initial free memory to improve memory-side-cache utilization 2019-05-14 19:52:48 -07:00
ipc ipc: do cyclic id allocation for the ipc object. 2019-05-14 19:52:52 -07:00
kernel Merge branch 'for-5.2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2019-05-16 19:01:23 -07:00
lib slab: remove /proc/slab_allocators 2019-05-16 15:51:55 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm slab: remove /proc/slab_allocators 2019-05-16 15:51:55 -07:00
net AFS fixes 2019-05-16 17:00:13 -07:00
samples Add gitignore file for samples/vfs/ generated files 2019-05-14 13:30:10 -07:00
scripts Kconfig updates for v5.2 2019-05-15 09:06:14 -07:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-05-13 15:15:00 -07:00
sound One more patch to remove io.h from clk-provider.h. We used to need this 2019-05-16 19:05:35 -07:00
tools linux-kselftest-5.2-rc1-2 2019-05-16 18:57:58 -07:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt mm/mmu_notifier: convert user range->blockable to helper function 2019-05-14 09:47:49 -07:00
.clang-format Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-17 11:26:25 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore .gitignore: add more all*.config patterns 2019-05-08 09:47:46 +09:00
.mailmap A reasonably busy cycle for docs, including: 2019-05-08 12:42:50 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Char/Misc driver patches for 5.1-rc1 2019-03-06 14:18:59 -08:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS nvme: update MAINTAINERS 2019-05-21 09:04:57 -06:00
Makefile Kbuild updates for v5.2 2019-05-08 12:25:12 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.