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Ryusuke Konishi b3a033e3ec nilfs2: fix potential deadlock with newly created symlinks 
Syzbot reported that page_symlink(), called by nilfs_symlink(), triggers
memory reclamation involving the filesystem layer, which can result in
circular lock dependencies among the reader/writer semaphore
nilfs->ns_segctor_sem, s_writers percpu_rwsem (intwrite) and the
fs_reclaim pseudo lock.

This is because after commit 21fc61c73c ("don't put symlink bodies in
pagecache into highmem"), the gfp flags of the page cache for symbolic
links are overwritten to GFP_KERNEL via inode_nohighmem().

This is not a problem for symlinks read from the backing device, because
the __GFP_FS flag is dropped after inode_nohighmem() is called.  However,
when a new symlink is created with nilfs_symlink(), the gfp flags remain
overwritten to GFP_KERNEL.  Then, memory allocation called from
page_symlink() etc.  triggers memory reclamation including the FS layer,
which may call nilfs_evict_inode() or nilfs_dirty_inode().  And these can
cause a deadlock if they are called while nilfs->ns_segctor_sem is held:

Fix this issue by dropping the __GFP_FS flag from the page cache GFP flags
of newly created symlinks in the same way that nilfs_new_inode() and
__nilfs_read_inode() do, as a workaround until we adopt nofs allocation
scope consistently or improve the locking constraints.

Link: https://lkml.kernel.org/r/20241020050003.4308-1-konishi.ryusuke@gmail.com
Fixes: 21fc61c73c ("don't put symlink bodies in pagecache into highmem")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+9ef37ac20608f4836256@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9ef37ac20608f4836256
Tested-by: syzbot+9ef37ac20608f4836256@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-10-30 20:14:12 -07:00
arch x86/traps: move kmsan check after instrumentation_begin 2024-10-28 21:40:39 -07:00
block block-6.12-20241026 2024-10-27 08:29:36 -10:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push fixes the following issues: 2024-10-16 08:42:54 -07:00
Documentation mseal: update mseal.rst 2024-10-28 21:40:41 -07:00
drivers platform-drivers-x86 for v6.12-3 2024-10-27 08:40:33 -10:00
fs nilfs2: fix potential deadlock with newly created symlinks 2024-10-30 20:14:12 -07:00
include mm, swap: avoid over reclaim of full clusters 2024-10-30 20:14:11 -07:00
init cfi: fix conditions for HAVE_CFI_ICALL_NORMALIZE_INTEGERS 2024-10-13 22:23:13 +02:00
io_uring io_uring/rw: fix wrong NOWAIT check in io_rw_init_file() 2024-10-19 09:25:45 -06:00
ipc struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
kernel resource,kexec: walk_system_ram_res_rev must retain resource flags 2024-10-28 21:40:40 -07:00
lib Probes fixes for v6.12-rc4(2): 2024-10-24 13:51:58 -07:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm kasan: remove vmalloc_percpu test 2024-10-30 20:14:11 -07:00
net BPF fixes: 2024-10-24 16:53:20 -07:00
rust Driver core fix for 6.12-rc3 2024-10-13 09:10:52 -07:00
samples [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
scripts kbuild: rust: add CONFIG_RUSTC_LLVM_VERSION 2024-10-13 22:22:28 +02:00
security ipe: fallback to platform keyring also if key in trusted keyring is rejected 2024-10-18 12:14:53 -07:00
sound ASoC: Fixes for v6.12 2024-10-24 07:57:39 +02:00
tools tools/mm: -Werror fixes in page-types/slabinfo 2024-10-30 20:14:11 -07:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt ARM64: 2024-10-21 11:22:04 -07:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.12 2024-09-24 13:02:06 -07:00
.mailmap Including fixes from netfiler, xfrm and bluetooth. 2024-10-24 16:43:50 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS CREDITS: sort alphabetically by name 2024-10-09 12:47:19 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS gpio fixes for v6.12-rc5 2024-10-25 10:47:51 -07:00
Makefile Linux 6.12-rc5 2024-10-27 12:52:02 -10:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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 reStructuredText 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.