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Linux kernel source tree
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Setting a large xattr value may require writing the attribute contents to an external inode. In this case we may need to lock the xattr inode along with the parent inode. This doesn't pose a deadlock risk because xattr inodes are not directly visible to the user and their access is restricted. Assign a lockdep subclass to xattr inode's lock. ============================================ WARNING: possible recursive locking detected 4.12.0-rc1+ #740 Not tainted -------------------------------------------- python/1822 is trying to acquire lock: (&sb->s_type->i_mutex_key#15){+.+...}, at: [<ffffffff804912ca>] ext4_xattr_set_entry+0x65a/0x7b0 but task is already holding lock: (&sb->s_type->i_mutex_key#15){+.+...}, at: [<ffffffff803d6687>] vfs_setxattr+0x57/0xb0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&sb->s_type->i_mutex_key#15); lock(&sb->s_type->i_mutex_key#15); *** DEADLOCK *** May be due to missing lock nesting notation 4 locks held by python/1822: #0: (sb_writers#10){.+.+.+}, at: [<ffffffff803d0eef>] mnt_want_write+0x1f/0x50 #1: (&sb->s_type->i_mutex_key#15){+.+...}, at: [<ffffffff803d6687>] vfs_setxattr+0x57/0xb0 #2: (jbd2_handle){.+.+..}, at: [<ffffffff80493f40>] start_this_handle+0xf0/0x420 #3: (&ei->xattr_sem){++++..}, at: [<ffffffff804920ba>] ext4_xattr_set_handle+0x9a/0x4f0 stack backtrace: CPU: 0 PID: 1822 Comm: python Not tainted 4.12.0-rc1+ #740 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: dump_stack+0x67/0x9e __lock_acquire+0x5f3/0x1750 lock_acquire+0xb5/0x1d0 down_write+0x2c/0x60 ext4_xattr_set_entry+0x65a/0x7b0 ext4_xattr_block_set+0x1b2/0x9b0 ext4_xattr_set_handle+0x322/0x4f0 ext4_xattr_set+0x144/0x1a0 ext4_xattr_user_set+0x34/0x40 __vfs_setxattr+0x66/0x80 __vfs_setxattr_noperm+0x69/0x1c0 vfs_setxattr+0xa2/0xb0 setxattr+0x12e/0x150 path_setxattr+0x87/0xb0 SyS_setxattr+0xf/0x20 entry_SYSCALL_64_fastpath+0x18/0xad Signed-off-by: Tahsin Erdogan <tahsin@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.