@@ -793,8 +793,10 @@ int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
phys_bytes = le64_to_cpu(rec.e_blkno) << osb->sb->s_blocksize_bits;
virt_bytes = (u64)le32_to_cpu(rec.e_cpos) << osb->s_clustersize_bits;
+ up_read(&OCFS2_I(inode)->ip_alloc_sem);
ret = fiemap_fill_next_extent(fieinfo, virt_bytes, phys_bytes,
len_bytes, fe_flags);
+ down_read(&OCFS2_I(inode)->ip_alloc_sem);
if (ret)
break;
@@ -119,9 +119,6 @@ static vm_fault_t ocfs2_page_mkwrite(struct vm_fault *vmf)
int err;
vm_fault_t ret;
- sb_start_pagefault(inode->i_sb);
- ocfs2_block_signals(&oldset);
-
/*
* The cluster locks taken will block a truncate from another
* node. Taking the data lock will also ensure that we don't
@@ -131,7 +128,7 @@ static vm_fault_t ocfs2_page_mkwrite(struct vm_fault *vmf)
if (err < 0) {
mlog_errno(err);
ret = vmf_error(err);
- goto out;
+ return ret;
}
/*
@@ -141,16 +138,19 @@ static vm_fault_t ocfs2_page_mkwrite(struct vm_fault *vmf)
*/
down_write(&OCFS2_I(inode)->ip_alloc_sem);
+ sb_start_pagefault(inode->i_sb);
+ ocfs2_block_signals(&oldset);
+
ret = __ocfs2_page_mkwrite(vmf->vma->vm_file, di_bh, page);
+ ocfs2_unblock_signals(&oldset);
+ sb_end_pagefault(inode->i_sb);
+
up_write(&OCFS2_I(inode)->ip_alloc_sem);
brelse(di_bh);
ocfs2_inode_unlock(inode, 1);
-out:
- ocfs2_unblock_signals(&oldset);
- sb_end_pagefault(inode->i_sb);
return ret;
}
Syzbot reported a possible circular locking dependency. WARNING: possible circular locking dependency detected 6.12.0-rc2-syzkaller-00205-g1d227fcc7222 #0 Not tainted ------------------------------------------------------ syz-executor161/5226 is trying to acquire lock: ffff88807e907398 (&mm->mmap_lock){++++}-{3:3}, at: __might_fault+0xaa/0x120 mm/memory.c:6700 but task is already holding lock: ffff8880720d0660 (&oi->ip_alloc_sem){++++}-{3:3}, at: ocfs2_fiemap+0x377/0xf80 fs/ocfs2/extent_map.c:755 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&oi->ip_alloc_sem){++++}-{3:3}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 down_write+0x99/0x220 kernel/locking/rwsem.c:1577 ocfs2_page_mkwrite+0x346/0xed0 fs/ocfs2/mmap.c:142 do_page_mkwrite+0x198/0x480 mm/memory.c:3162 do_shared_fault mm/memory.c:5358 [inline] do_fault mm/memory.c:5420 [inline] do_pte_missing mm/memory.c:3965 [inline] handle_pte_fault+0x11fa/0x6800 mm/memory.c:5751 __handle_mm_fault mm/memory.c:5894 [inline] handle_mm_fault+0x1053/0x1ad0 mm/memory.c:6062 do_user_addr_fault arch/x86/mm/fault.c:1389 [inline] handle_page_fault arch/x86/mm/fault.c:1481 [inline] exc_page_fault+0x2b9/0x8c0 arch/x86/mm/fault.c:1539 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 -> #1 (sb_pagefaults){.+.+}-{0:0}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1716 [inline] sb_start_pagefault include/linux/fs.h:1881 [inline] ocfs2_page_mkwrite+0x222/0xed0 fs/ocfs2/mmap.c:122 do_page_mkwrite+0x198/0x480 mm/memory.c:3162 do_shared_fault mm/memory.c:5358 [inline] do_fault mm/memory.c:5420 [inline] do_pte_missing mm/memory.c:3965 [inline] handle_pte_fault+0x11fa/0x6800 mm/memory.c:5751 __handle_mm_fault mm/memory.c:5894 [inline] handle_mm_fault+0x1053/0x1ad0 mm/memory.c:6062 do_user_addr_fault arch/x86/mm/fault.c:1389 [inline] handle_page_fault arch/x86/mm/fault.c:1481 [inline] exc_page_fault+0x2b9/0x8c0 arch/x86/mm/fault.c:1539 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 -> #0 (&mm->mmap_lock){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __might_fault+0xc6/0x120 mm/memory.c:6700 _inline_copy_to_user include/linux/uaccess.h:183 [inline] _copy_to_user+0x2a/0xb0 lib/usercopy.c:26 copy_to_user include/linux/uaccess.h:216 [inline] fiemap_fill_next_extent+0x235/0x410 fs/ioctl.c:145 ocfs2_fiemap+0x9f1/0xf80 fs/ocfs2/extent_map.c:796 ioctl_fiemap fs/ioctl.c:220 [inline] do_vfs_ioctl+0x1bf8/0x2e40 fs/ioctl.c:841 __do_sys_ioctl fs/ioctl.c:905 [inline] __se_sys_ioctl+0x81/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &mm->mmap_lock --> sb_pagefaults --> &oi->ip_alloc_sem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&oi->ip_alloc_sem); lock(sb_pagefaults); lock(&oi->ip_alloc_sem); rlock(&mm->mmap_lock); *** DEADLOCK *** Fix it by reordering locks sb_pagefaults and ip_alloc_sem, because fiemap_fill_next_extent() does not need to be in the lock ip_alloc_sem, cancel and retrieve ip_alloc_sem before and after the execution of it. Reported-and-tested-by: syzbot+ca440b457d21568f8021@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=ca440b457d21568f8021 Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com> --- fs/ocfs2/extent_map.c | 2 ++ fs/ocfs2/mmap.c | 14 +++++++------- 2 files changed, 9 insertions(+), 7 deletions(-)