Commit 4763d635 authored Nov 21, 2023 by Steven Rostedt (Google)

eventfs: Use GFP_NOFS for allocation when eventfs_mutex is held

If memory reclaim happens, it can reclaim file system pages. The file
system pages from eventfs may take the eventfs_mutex on reclaim. This
means that allocation while holding the eventfs_mutex must not call into
filesystem reclaim. A lockdep splat uncovered this.

Link: https://lkml.kernel.org/r/20231121231112.373501894@goodmis.org



Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: 28e12c09 ("eventfs: Save ownership and mode")
Fixes: 5790b1fb ("eventfs: Remove eventfs_file and just use eventfs_inode")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

parent 71cade82

fs/tracefs/event_inode.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -95,7 +95,7 @@ static int eventfs_set_attr(struct mnt_idmap idmap, struct dentry dentry,
		if (!(dentry->d_inode->i_mode & S_IFDIR)) {
		if (!ei->entry_attrs) {
		ei->entry_attrs = kzalloc(sizeof(ei->entry_attrs) ei->nr_entries,
		GFP_KERNEL);
		GFP_NOFS);
		if (!ei->entry_attrs) {
		ret = -ENOMEM;
		goto out;
		@@ -627,7 +627,7 @@ static int add_dentries(struct dentry **dentries, struct dentry d, int cnt)
		{
		struct dentry **tmp;

		tmp = krealloc(dentries, sizeof(d) (cnt + 2), GFP_KERNEL);
		tmp = krealloc(dentries, sizeof(d) (cnt + 2), GFP_NOFS);
		if (!tmp)
		return -1;
		tmp[cnt] = d;