From 7131aaa74bcc7c9da1f1d1c8724da75c775557a0 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Wed, 30 Sep 2026 03:26:54 +0900 Subject: [PATCH] nilfs2: ignore non-fatal signals during synchronous log write wait Based on a syzbot report, Wang Jianjian pointed out that following a successful directory operation in nilfs_rename(), a synchronous write requested within nilfs_transaction_commit(), triggered by a sync flag set by nilfs_commit_chunk(), could be interrupted by a user signal. This interruption leaves in-memory metadata updates intact while returning an error, causing inconsistency with the VFS dentry cache and ultimately triggering a kernel warning. According to "signal(7)", local disks are not classified as "slow devices" (such as terminals, FIFOs, or pipes) and their I/O operations on disk devices are not interrupted by signals. In kernel space, waiting for such disk I/O should therefore not be aborted by ordinary (non-fatal) signals. Suppress this issue by modifying nilfs_segctor_sync(), which waits for the log writer thread to complete synchronous writes, to catch only fatal signals via fatal_signal_pending() and return -EINTR rather than -ERESTARTSYS. To complement this change and prevent the wait loop from busy-looping when schedule() returns immediately due to a pending non-fatal signal, switch the wait state from TASK_INTERRUPTIBLE to TASK_KILLABLE. This serves as an effective interim stabilization measure without structural changes until a comprehensive fix for metadata consistency is implemented. Reported-by: syzbot+f6c7e1f1809f235eeb90@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f6c7e1f1809f235eeb90 Fixes: 9ff05123e3bf ("nilfs2: segment constructor") Tested-by: syzbot+f6c7e1f1809f235eeb90@syzkaller.appspotmail.com Cc: Wang Jianjian Cc: stable@vger.kernel.org Signed-off-by: Ryusuke Konishi Signed-off-by: Viacheslav Dubeyko --- fs/nilfs2/ioctl.c | 2 +- fs/nilfs2/recovery.c | 2 +- fs/nilfs2/segment.c | 10 +++++----- 3 files changed, 7 insertions(+), 7 deletions(-) diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c index 01a04080ef70..b2b67d6a1f09 100644 --- a/fs/nilfs2/ioctl.c +++ b/fs/nilfs2/ioctl.c @@ -965,10 +965,10 @@ static int nilfs_ioctl_clean_segments(struct inode *inode, struct file *filp, * Return: 0 on success, or one of the following negative error codes on * failure: * * %-EFAULT - Failure during execution of requested operation. + * * %-EINTR - Interrupted. * * %-EIO - I/O error. * * %-ENOMEM - Insufficient memory available. * * %-ENOSPC - No space left on device (only in a panic state). - * * %-ERESTARTSYS - Interrupted. * * %-EROFS - Read only filesystem. */ static int nilfs_ioctl_sync(struct inode *inode, struct file *filp, diff --git a/fs/nilfs2/recovery.c b/fs/nilfs2/recovery.c index 9a70c28ec94c..abe4101f7550 100644 --- a/fs/nilfs2/recovery.c +++ b/fs/nilfs2/recovery.c @@ -790,11 +790,11 @@ static void nilfs_abort_roll_forward(struct the_nilfs *nilfs) * * Return: 0 on success, or one of the following negative error codes on * failure: + * * %-EINTR - Interrupted. * * %-EINVAL - Inconsistent filesystem state. * * %-EIO - I/O error. * * %-ENOMEM - Insufficient memory available. * * %-ENOSPC - No space left on device (only in a panic state). - * * %-ERESTARTSYS - Interrupted. */ int nilfs_salvage_orphan_logs(struct the_nilfs *nilfs, struct super_block *sb, diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c index 2f0e59847d02..af0c3560444f 100644 --- a/fs/nilfs2/segment.c +++ b/fs/nilfs2/segment.c @@ -2259,7 +2259,7 @@ static int nilfs_segctor_sync(struct nilfs_sc_info *sci) wake_up(&sci->sc_wait_daemon); for (;;) { - set_current_state(TASK_INTERRUPTIBLE); + set_current_state(TASK_KILLABLE); /* * Synchronize only while the log writer thread is alive. @@ -2273,11 +2273,11 @@ static int nilfs_segctor_sync(struct nilfs_sc_info *sci) err = wait_req.err; break; } - if (!signal_pending(current)) { + if (!fatal_signal_pending(current)) { schedule(); continue; } - err = -ERESTARTSYS; + err = -EINTR; break; } finish_wait(&sci->sc_wait_request, &wait_req.wq); @@ -2311,10 +2311,10 @@ static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err, bool force) * * Return: 0 on success, or one of the following negative error codes on * failure: + * * %-EINTR - Interrupted. * * %-EIO - I/O error (including metadata corruption). * * %-ENOMEM - Insufficient memory available. * * %-ENOSPC - No space left on device (only in a panic state). - * * %-ERESTARTSYS - Interrupted. * * %-EROFS - Read only filesystem. */ int nilfs_construct_segment(struct super_block *sb) @@ -2341,10 +2341,10 @@ int nilfs_construct_segment(struct super_block *sb) * * Return: 0 on success, or one of the following negative error codes on * failure: + * * %-EINTR - Interrupted. * * %-EIO - I/O error (including metadata corruption). * * %-ENOMEM - Insufficient memory available. * * %-ENOSPC - No space left on device (only in a panic state). - * * %-ERESTARTSYS - Interrupted. * * %-EROFS - Read only filesystem. */ int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,