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Ryusuke Konishi e897be17a4 nilfs2: fix lockdep warnings in page operations for btree nodes
Patch series "nilfs2 lockdep warning fixes".

The first two are to resolve the lockdep warning issue, and the last one
is the accompanying cleanup and low priority.

Based on your comment, this series solves the issue by separating inode
object as needed.  Since I was worried about the impact of the object
composition changes, I tested the series carefully not to cause
regressions especially for delicate functions such like disk space
reclamation and snapshots.

This patch (of 3):

If CONFIG_LOCKDEP is enabled, nilfs2 hits lockdep warnings at
inode_to_wb() during page/folio operations for btree nodes:

  WARNING: CPU: 0 PID: 6575 at include/linux/backing-dev.h:269 inode_to_wb include/linux/backing-dev.h:269 [inline]
  WARNING: CPU: 0 PID: 6575 at include/linux/backing-dev.h:269 folio_account_dirtied mm/page-writeback.c:2460 [inline]
  WARNING: CPU: 0 PID: 6575 at include/linux/backing-dev.h:269 __folio_mark_dirty+0xa7c/0xe30 mm/page-writeback.c:2509
  Modules linked in:
  ...
  RIP: 0010:inode_to_wb include/linux/backing-dev.h:269 [inline]
  RIP: 0010:folio_account_dirtied mm/page-writeback.c:2460 [inline]
  RIP: 0010:__folio_mark_dirty+0xa7c/0xe30 mm/page-writeback.c:2509
  ...
  Call Trace:
    __set_page_dirty include/linux/pagemap.h:834 [inline]
    mark_buffer_dirty+0x4e6/0x650 fs/buffer.c:1145
    nilfs_btree_propagate_p fs/nilfs2/btree.c:1889 [inline]
    nilfs_btree_propagate+0x4ae/0xea0 fs/nilfs2/btree.c:2085
    nilfs_bmap_propagate+0x73/0x170 fs/nilfs2/bmap.c:337
    nilfs_collect_dat_data+0x45/0xd0 fs/nilfs2/segment.c:625
    nilfs_segctor_apply_buffers+0x14a/0x470 fs/nilfs2/segment.c:1009
    nilfs_segctor_scan_file+0x47a/0x700 fs/nilfs2/segment.c:1048
    nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1224 [inline]
    nilfs_segctor_collect fs/nilfs2/segment.c:1494 [inline]
    nilfs_segctor_do_construct+0x14f3/0x6c60 fs/nilfs2/segment.c:2036
    nilfs_segctor_construct+0x7a7/0xb30 fs/nilfs2/segment.c:2372
    nilfs_segctor_thread_construct fs/nilfs2/segment.c:2480 [inline]
    nilfs_segctor_thread+0x3c3/0xf90 fs/nilfs2/segment.c:2563
    kthread+0x405/0x4f0 kernel/kthread.c:327
    ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

This is because nilfs2 uses two page caches for each inode and
inode->i_mapping never points to one of them, the btree node cache.

This causes inode_to_wb(inode) to refer to a different page cache than
the caller page/folio operations such like __folio_start_writeback(),
__folio_end_writeback(), or __folio_mark_dirty() acquired the lock.

This patch resolves the issue by allocating and using an additional
inode to hold the page cache of btree nodes.  The inode is attached
one-to-one to the traditional nilfs2 inode if it requires a block
mapping with b-tree.  This setup change is in memory only and does not
affect the disk format.

Link: https://lkml.kernel.org/r/1647867427-30498-1-git-send-email-konishi.ryusuke@gmail.com
Link: https://lkml.kernel.org/r/1647867427-30498-2-git-send-email-konishi.ryusuke@gmail.com
Link: https://lore.kernel.org/r/YXrYvIo8YRnAOJCj@casper.infradead.org
Link: https://lore.kernel.org/r/9a20b33d-b38f-b4a2-4742-c1eb5b8e4d6c@redhat.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+0d5b462a6f07447991b3@syzkaller.appspotmail.com
Reported-by: syzbot+34ef28bb2aeb28724aa0@syzkaller.appspotmail.com
Reported-by: Hao Sun <sunhao.th@gmail.com>
Reported-by: David Hildenbrand <david@redhat.com>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-04-01 11:46:09 -07:00
arch This pull request contains the following changes for UML: 2022-03-31 16:16:58 -07:00
block ptrace: Cleanups for v5.18 2022-03-28 17:29:53 -07:00
certs Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
crypto for-5.18/64bit-pi-2022-03-25 2022-03-26 12:01:35 -07:00
Documentation This pull request contains the following changes for UML: 2022-03-31 16:16:58 -07:00
drivers This pull request contains fixes for JFFS2, UBI and UBIFS 2022-03-31 16:09:41 -07:00
fs nilfs2: fix lockdep warnings in page operations for btree nodes 2022-04-01 11:46:09 -07:00
include Netfs prep for write helpers 2022-03-31 15:49:36 -07:00
init Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
ipc fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
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LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm Revert "mm: madvise: skip unmapped vma holes passed to process_madvise" 2022-04-01 11:46:09 -07:00
net Networking fixes for 5.18-rc1 and rethook patches. 2022-03-31 11:23:31 -07:00
samples dma-mapping updates for Linux 5.18 2022-03-29 08:50:14 -07:00
scripts Some late-arriving documentation improvements. This is mostly build-system 2022-03-31 12:10:42 -07:00
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COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
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 This pull request contains the following changes for UML: 2022-03-31 16:16:58 -07:00
Makefile Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
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Please read the Documentation/process/changes.rst file, as it contains the
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