linux-kernel - Re: [syzbot] [ocfs2?] possible deadlock in ocfs2_nfs_sync

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Message-Id: <20240831122756.1426-1-hdanton@sina.com>
Date: Sat, 31 Aug 2024 20:27:56 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+fcb79916dcfe2a4ed10a@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [ocfs2?] possible deadlock in ocfs2_nfs_sync_lock

On Sat, 31 Aug 2024 02:46:20 -0700
> syzbot found the following issue on:
> 
> HEAD commit:    a18093afa393 Merge tag 'nfsd-6.11-2' of git://git.kernel.o..
> git tree:       upstream
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11f51063980000

#syz test upstream  a18093afa393

--- l/fs/ocfs2/suballoc.c
+++ k/fs/ocfs2/suballoc.c
@@ -962,8 +962,10 @@ int ocfs2_reserve_new_metadata_blocks(st
 {
 	int status;
 	int slot = ocfs2_get_meta_steal_slot(osb);
+	unsigned int pff = memalloc_nofs_save();
 
 	*ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
+	memalloc_nofs_restore(pff);
 	if (!(*ac)) {
 		status = -ENOMEM;
 		mlog_errno(status);
--