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Yonatan Cohen 9ea04d0df6 IB/umad: Fix kernel crash while unloading ib_umad
When disassociating a device from umad we must ensure that the sysfs
access is prevented before blocking the fops, otherwise assumptions in
syfs don't hold:

	    CPU0            	        CPU1
	 ib_umad_kill_port()        ibdev_show()
	    port->ib_dev = NULL
                                      dev_name(port->ib_dev)

The prior patch made an error in moving the device_destroy(), it should
have been split into device_del() (above) and put_device() (below). At
this point we already have the split, so move the device_del() back to its
original place.

  kernel stack
  PF: error_code(0x0000) - not-present page
  Oops: 0000 [#1] SMP DEBUG_PAGEALLOC PTI
  RIP: 0010:ibdev_show+0x18/0x50 [ib_umad]
  RSP: 0018:ffffc9000097fe40 EFLAGS: 00010282
  RAX: 0000000000000000 RBX: ffffffffa0441120 RCX: ffff8881df514000
  RDX: ffff8881df514000 RSI: ffffffffa0441120 RDI: ffff8881df1e8870
  RBP: ffffffff81caf000 R08: ffff8881df1e8870 R09: 0000000000000000
  R10: 0000000000001000 R11: 0000000000000003 R12: ffff88822f550b40
  R13: 0000000000000001 R14: ffffc9000097ff08 R15: ffff8882238bad58
  FS:  00007f1437ff3740(0000) GS:ffff888236940000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00000000000004e8 CR3: 00000001e0dfc001 CR4: 00000000001606e0
  Call Trace:
   dev_attr_show+0x15/0x50
   sysfs_kf_seq_show+0xb8/0x1a0
   seq_read+0x12d/0x350
   vfs_read+0x89/0x140
   ksys_read+0x55/0xd0
   do_syscall_64+0x55/0x1b0
   entry_SYSCALL_64_after_hwframe+0x44/0xa9:

Fixes: cf7ad30302 ("IB/umad: Avoid destroying device while it is accessed")
Link: https://lore.kernel.org/r/20200212072635.682689-9-leon@kernel.org
Signed-off-by: Yonatan Cohen <yonatanc@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
2020-02-13 10:00:50 -04:00
arch Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
block block-5.6-2020-02-05 2020-02-06 06:15:23 +00:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto treewide: remove redundant IS_ERR() before error code check 2020-02-04 03:05:27 +00:00
Documentation Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
drivers IB/umad: Fix kernel crash while unloading ib_umad 2020-02-13 10:00:50 -04:00
fs Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
include fs: New zonefs file system 2020-02-09 15:51:46 -08:00
init Tracing updates: 2020-02-06 07:12:11 +00:00
ipc proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
kernel Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
lib Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm Merge branch 'merge.nfs-fs_parse.1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-02-08 13:26:41 -08:00
net Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
samples Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
scripts Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
security Merge branch 'merge.nfs-fs_parse.1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-02-08 13:26:41 -08:00
sound sound fixes for 5.6-rc1 2020-02-06 14:15:01 +00:00
tools A set of fixes and improvements for the perf subsystem: 2020-02-09 12:04:09 -08:00
usr Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
virt KVM: fix overflow of zero page refcount with ksm running 2020-02-05 15:27:46 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
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.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap A handful of small documentation fixes that wandered in. 2020-02-07 13:03:10 -08:00
COPYING
CREDITS open: introduce openat2(2) syscall 2020-01-18 09:19:18 -05:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS fs: New zonefs file system 2020-02-09 15:51:46 -08:00
Makefile Linux 5.6-rc1 2020-02-09 16:08:48 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.