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Dan Williams 956a4cd2c9 device-dax: switch to srcu, fix rcu_read_lock() vs pte allocation
The following warning triggers with a new unit test that stresses the
device-dax interface.

 ===============================
 [ ERR: suspicious RCU usage.  ]
 4.11.0-rc4+ #1049 Tainted: G           O
 -------------------------------
 ./include/linux/rcupdate.h:521 Illegal context switch in RCU read-side critical section!

 other info that might help us debug this:

 rcu_scheduler_active = 2, debug_locks = 0
 2 locks held by fio/9070:
  #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff8d0739d7>] __do_page_fault+0x167/0x4f0
  #1:  (rcu_read_lock){......}, at: [<ffffffffc03fbd02>] dax_dev_huge_fault+0x32/0x620 [dax]

 Call Trace:
  dump_stack+0x86/0xc3
  lockdep_rcu_suspicious+0xd7/0x110
  ___might_sleep+0xac/0x250
  __might_sleep+0x4a/0x80
  __alloc_pages_nodemask+0x23a/0x360
  alloc_pages_current+0xa1/0x1f0
  pte_alloc_one+0x17/0x80
  __pte_alloc+0x1e/0x120
  __get_locked_pte+0x1bf/0x1d0
  insert_pfn.isra.70+0x3a/0x100
  ? lookup_memtype+0xa6/0xd0
  vm_insert_mixed+0x64/0x90
  dax_dev_huge_fault+0x520/0x620 [dax]
  ? dax_dev_huge_fault+0x32/0x620 [dax]
  dax_dev_fault+0x10/0x20 [dax]
  __do_fault+0x1e/0x140
  __handle_mm_fault+0x9af/0x10d0
  handle_mm_fault+0x16d/0x370
  ? handle_mm_fault+0x47/0x370
  __do_page_fault+0x28c/0x4f0
  trace_do_page_fault+0x58/0x2a0
  do_async_page_fault+0x1a/0xa0
  async_page_fault+0x28/0x30

Inserting a page table entry may trigger an allocation while we are
holding a read lock to keep the device instance alive for the duration
of the fault. Use srcu for this keep-alive protection.

Fixes: dee4107924 ("/dev/dax, core: file operations and dax-mmap")
Cc: <stable@vger.kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-04-12 13:45:18 -07:00
arch powerpc fixes for 4.11 #6 2017-03-26 10:34:10 -07:00
block blk-mq: don't complete un-started request in timeout handler 2017-03-22 08:03:35 -06:00
certs certs: Add a secondary system keyring that can be added to dynamically 2016-04-11 22:48:09 +01:00
crypto net: Work around lockdep limitation in sockets that use sockets 2017-03-09 18:23:27 -08:00
Documentation Char/Misc driver fixes for 4.11-rc4 2017-03-26 11:15:54 -07:00
drivers device-dax: switch to srcu, fix rcu_read_lock() vs pte allocation 2017-04-12 13:45:18 -07:00
firmware WHENCE: use https://linuxtv.org for LinuxTV URLs 2015-12-04 10:35:11 -02:00
fs driver core fix for 4.11-rc4 2017-03-26 11:05:42 -07:00
include Char/Misc driver fixes for 4.11-rc4 2017-03-26 11:15:54 -07:00
init Change get_random_{int,log} to use the CRNG used by /dev/urandom and 2017-03-11 09:08:47 -08:00
ipc Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
kernel Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit 2017-03-25 15:13:55 -07:00
lib mm: convert generic code to 5-level paging 2017-03-09 11:48:47 -08:00
mm mm, swap: Remove WARN_ON_ONCE() in free_swap_slot() 2017-03-21 14:13:19 -07:00
net A fix for a writeback deadlock caused by a GFP_KERNEL allocation on the 2017-03-24 14:35:39 -07:00
samples Merge branch 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-03-03 11:38:56 -08:00
scripts Merge branch 'akpm' (patches from Andrew) 2017-03-10 08:34:42 -08:00
security Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
sound ALSA: hda - Adding a group of pin definition to fix headset problem 2017-03-23 09:39:55 +01:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-03-23 11:29:49 -07:00
usr kbuild: initramfs cleanup, set target from Kconfig 2017-01-05 09:40:16 -08:00
virt KVM: arm/arm64: VGIC: Fix command handling while ITS being disabled 2017-03-07 15:44:08 +00:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
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.gitignore Merge branch 'misc' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-08-02 16:48:52 -04:00
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COPYING
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Kbuild scripts/gdb: provide linux constants 2016-05-23 17:04:14 -07:00
Kconfig
MAINTAINERS enic: update enic maintainers 2017-03-22 12:48:55 -07:00
Makefile Linux 4.11-rc4 2017-03-26 14:15:16 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

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.