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Filename Latest commit message Latest commit date
Jeff Layton e9b2b2b29c ceph: take snap_empty_lock atomically with snaprealm refcount change
commit 8434ffe71c874b9c4e184b88d25de98c2bf5fe3f upstream.

There is a race in ceph_put_snap_realm. The change to the nref and the
spinlock acquisition are not done atomically, so you could decrement
nref, and before you take the spinlock, the nref is incremented again.
At that point, you end up putting it on the empty list when it
shouldn't be there. Eventually __cleanup_empty_realms runs and frees
it when it's still in-use.

Fix this by protecting the 1->0 transition with atomic_dec_and_lock,
and just drop the spinlock if we can get the rwsem.

Because these objects can also undergo a 0->1 refcount transition, we
must protect that change as well with the spinlock. Increment locklessly
unless the value is at 0, in which case we take the spinlock, increment
and then take it off the empty list if it did the 0->1 transition.

With these changes, I'm removing the dout() messages from these
functions, as well as in __put_snap_realm. They've always been racy, and
it's better to not print values that may be misleading.

Cc: stable@vger.kernel.org
URL: https://tracker.ceph.com/issues/46419
Reported-by: Mark Nelson <mnelson@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Luis Henriques <lhenriques@suse.de>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-08-18 08:57:04 +02:00
arch KVM: VMX: Use current VMCS to query WAITPKG support for MSR emulation 2021-08-18 08:57:03 +02:00
block blk-iolatency: error out if blk_get_queue() failed in iolatency_set_limit() 2021-08-12 13:20:58 +02:00
certs certs: Move load_system_certificate_list to a common function 2021-06-30 08:47:55 -04:00
crypto crypto: shash - avoid comparing pointers to exported functions under CFI 2021-07-14 16:53:13 +02:00
Documentation KVM: X86: MMU: Use the correct inherited permissions to get shadow page 2021-08-15 13:08:04 +02:00
drivers PCI/MSI: Protect msi_desc::masked for multi-MSI 2021-08-18 08:57:03 +02:00
fs ceph: take snap_empty_lock atomically with snaprealm refcount change 2021-08-18 08:57:04 +02:00
include PCI/MSI: Protect msi_desc::masked for multi-MSI 2021-08-18 08:57:03 +02:00
init kbuild: add CONFIG_LD_IS_LLD 2021-06-30 08:47:44 -04:00
ipc
kernel genirq/timings: Prevent potential array overflow in __irq_timings_store() 2021-08-18 08:57:02 +02:00
lib lib/decompress_unlz4.c: correctly handle zero-padding around initrds. 2021-07-20 16:10:46 +02:00
LICENSES
mm mm: slab: fix kmem_cache_create failed when sysfs node not destroyed 2021-07-25 14:35:14 +02:00
net vsock/virtio: avoid potential deadlock when vsock device remove 2021-08-18 08:57:01 +02:00
samples samples/bpf: Fix the error return code of xdp_redirect's main() 2021-07-14 16:53:30 +02:00
scripts scripts/tracing: fix the bug that can't parse raw_trace_func 2021-08-12 13:21:00 +02:00
security smackfs: restrict bytes count in smk_set_cipso() 2021-07-19 08:53:18 +02:00
sound ASoC: cs42l42: Fix LRCLK frame start edge 2021-08-18 08:56:58 +02:00
tools bpf, selftests: Adjust few selftest result_unpriv outcomes 2021-08-12 13:21:04 +02:00
usr
virt KVM: Do not leak memory for duplicate debugfs directories 2021-08-12 13:21:03 +02:00
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Makefile Linux 5.4.141 2021-08-15 13:08:06 +02:00
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.