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Filename Latest commit message Latest commit date
Jan Kara 8635f0fe06 ext4: fix deadlock with fs freezing and EA inodes
commit 46e294efc355c48d1dd4d58501aa56dac461792a upstream.

Xattr code using inodes with large xattr data can end up dropping last
inode reference (and thus deleting the inode) from places like
ext4_xattr_set_entry(). That function is called with transaction started
and so ext4_evict_inode() can deadlock against fs freezing like:

CPU1					CPU2

removexattr()				freeze_super()
  vfs_removexattr()
    ext4_xattr_set()
      handle = ext4_journal_start()
      ...
      ext4_xattr_set_entry()
        iput(old_ea_inode)
          ext4_evict_inode(old_ea_inode)
					  sb->s_writers.frozen = SB_FREEZE_FS;
					  sb_wait_write(sb, SB_FREEZE_FS);
					  ext4_freeze()
					    jbd2_journal_lock_updates()
					      -> blocks waiting for all
					         handles to stop
            sb_start_intwrite()
	      -> blocks as sb is already in SB_FREEZE_FS state

Generally it is advisable to delete inodes from a separate transaction
as it can consume quite some credits however in this case it would be
quite clumsy and furthermore the credits for inode deletion are quite
limited and already accounted for. So just tweak ext4_evict_inode() to
avoid freeze protection if we have transaction already started and thus
it is not really needed anyway.

Cc: stable@vger.kernel.org
Fixes: dec214d00e ("ext4: xattr inode deduplication")
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/20201127110649.24730-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-12-30 11:51:37 +01:00
arch crypto: arm/aes-ce - work around Cortex-A57/A72 silion errata 2020-12-30 11:51:36 +01:00
block blk-mq: In blk_mq_dispatch_rq_list() "no budget" is a reason to kick 2020-12-30 11:50:54 +01:00
certs
crypto crypto: ecdh - avoid unaligned accesses in ecdh_set_secret() 2020-12-30 11:51:35 +01:00
Documentation KVM: mmu: Fix SPTE encoding of MMIO generation upper half 2020-12-21 13:27:06 +01:00
drivers USB: serial: keyspan_pda: fix write unthrottling 2020-12-30 11:51:37 +01:00
fs ext4: fix deadlock with fs freezing and EA inodes 2020-12-30 11:51:37 +01:00
include binder: add flag to clear buffer on txn complete 2020-12-30 11:51:35 +01:00
init initramfs: fix clang build failure 2020-12-30 11:51:30 +01:00
ipc
kernel cpuset: fix race between hotplug work and later CPU offline 2020-12-30 11:51:36 +01:00
lib lib/syscall: fix syscall registers retrieval on 32-bit platforms 2020-12-11 13:23:32 +01:00
LICENSES
mm mm: don't wake kswapd prematurely when watermark boosting is disabled 2020-12-30 11:51:27 +01:00
net lwt: Disable BH too in run_lwt_bpf() 2020-12-30 11:51:30 +01:00
samples samples: bpf: Fix lwt_len_hist reusing previous BPF map 2020-12-30 11:51:12 +01:00
scripts kconfig: fix return value of do_error_if() 2020-12-30 11:51:29 +01:00
security selinux: fix inode_doinit_with_dentry() LABEL_INVALID error handling 2020-12-30 11:51:05 +01:00
sound ASoC: cx2072x: Fix doubly definitions of Playback and Capture streams 2020-12-30 11:51:35 +01:00
tools perf probe: Fix memory leak when synthesizing SDT probes 2020-12-30 11:51:29 +01:00
usr
virt KVM: arm64: vgic-v3: Drop the reporting of GICR_TYPER.Last for userspace 2020-12-02 08:49:46 +01:00
.clang-format
.cocciconfig
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.gitignore
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COPYING
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Kconfig
MAINTAINERS
Makefile Linux 5.4.85 2020-12-21 13:27:07 +01:00
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.