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Ian Kent 410d591a19 kernfs: don't create a negative dentry if inactive node exists
It's been reported that doing stress test for module insertion and
removal can result in an ENOENT from libkmod for a valid module.

In kernfs_iop_lookup() a negative dentry is created if there's no kernfs
node associated with the dentry or the node is inactive.

But inactive kernfs nodes are meant to be invisible to the VFS and
creating a negative dentry for these can have unexpected side effects
when the node transitions to an active state.

The point of creating negative dentries is to avoid the expensive
alloc/free cycle that occurs if there are frequent lookups for kernfs
attributes that don't exist. So kernfs nodes that are not yet active
should not result in a negative dentry being created so when they
transition to an active state VFS lookups can create an associated
dentry is a natural way.

It's also been reported that https://github.com/osandov/blktests.git
test block/001 hangs during the test. It was suggested that recent
changes to blktests might have caused it but applying this patch
resolved the problem without change to blktests.

Fixes: c7e7c04274 ("kernfs: use VFS negative dentry caching")
Tested-by: Yi Zhang <yi.zhang@redhat.com>
ACKed-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Ian Kent <raven@themaw.net>
Link: https://lore.kernel.org/r/163330943316.19450.15056895533949392922.stgit@mickey.themaw.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-04 10:27:18 +02:00
arch kvm: fix objtool relocation warning 2021-10-03 13:34:19 -07:00
block block-5.15-2021-10-01 2021-10-02 11:00:36 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2021-08-30 12:57:10 -07:00
Documentation Char/Misc driver fixes for 5.15-rc4 2021-10-03 11:19:02 -07:00
drivers Char/Misc driver fixes for 5.15-rc4 2021-10-03 11:19:02 -07:00
fs kernfs: don't create a negative dentry if inactive node exists 2021-10-04 10:27:18 +02:00
include Driver core fixes for 5.15-rc4 2021-10-03 11:10:09 -07:00
init Merge branch 'work.init' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-09-24 10:18:07 -07:00
ipc ipc: remove memcg accounting for sops objects in do_semtimedop() 2021-09-14 10:22:11 -07:00
kernel - Tell the compiler to always inline is_percpu_thread() 2021-10-03 10:49:00 -07:00
lib lib/zlib_inflate/inffast: check config in C to avoid unused function warning 2021-09-24 16:13:35 -07:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm: fix uninitialized use in overcommit_policy_handler 2021-09-24 16:13:35 -07:00
net af_unix: fix races in sk_peer_pid and sk_peer_cred accesses 2021-09-30 14:18:40 +01:00
samples kgdb patches for 5.15 2021-09-07 12:08:04 -07:00
scripts kasan: always respect CONFIG_KASAN_STACK 2021-09-24 16:13:35 -07:00
security selinux,smack: fix subjective/objective credential use mixups 2021-09-23 12:30:59 -04:00
sound ALSA: pcsp: Make hrtimer forwarding more robust 2021-09-28 10:58:08 +02:00
tools objtool: print out the symbol type when complaining about it 2021-10-03 13:45:48 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Remove tlbs_dirty 2021-09-23 11:01:12 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update email address of Matthias Fuchs and Thomas Körper 2021-08-19 09:39:44 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Eleven fixes for the ksmbd kernel server, including an important fix disabling weak NTLMv1 authentication, and seven security (improved buffer overflow checks) fixes 2021-10-02 17:43:54 -07:00
Makefile Linux 5.15-rc4 2021-10-03 14:08:47 -07:00
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.