linux-kernel - Re: [syzbot] Re: [keyrings?] [lsm?] [ext4?] possible deadlock in keyring

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Message-ID: <66f6ba76.050a0220.46d20.0019.GAE@google.com>
Date: Fri, 27 Sep 2024 07:00:22 -0700
From: syzbot <syzbot+1b2d1134e0b675176a15@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org
Subject: Re: [syzbot] Re: [keyrings?] [lsm?] [ext4?] possible deadlock in
 keyring_clear (2)

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Subject: Re: [keyrings?] [lsm?] [ext4?] possible deadlock in keyring_clear (2)
Author: lizhi.xu@...driver.com

tmp no use nofs

#syz test

diff --git a/init/main.c b/init/main.c
index c4778edae797..7e08a69fc432 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1261,12 +1261,15 @@ int __init_or_module do_one_initcall(initcall_t fn)
 	int count = preempt_count();
 	char msgbuf[64];
 	int ret;
+	unsigned int nofs_flag;
 
 	if (initcall_blacklisted(fn))
 		return -EPERM;
 
 	do_trace_initcall_start(fn);
+	nofs_flag = memalloc_nofs_save();
 	ret = fn();
+	memalloc_nofs_restore(nofs_flag);
 	do_trace_initcall_finish(fn, ret);
 
 	msgbuf[0] = 0;
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 1c77400bd88e..fa16932f799d 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -1623,7 +1623,12 @@ static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 
 long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
-	return __ext4_ioctl(filp, cmd, arg);
+	long ret;
+	unsigned int nofs_flag;
+	nofs_flag = memalloc_nofs_save();
+	ret = __ext4_ioctl(filp, cmd, arg);
+	memalloc_nofs_restore(nofs_flag);
+	return ret;
 }
 
 #ifdef CONFIG_COMPAT