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Subject: Re: inconsistent lock state in io_file_data_ref_zero
To:     syzbot <syzbot+1f4ba1e5520762c523c6@syzkaller.appspotmail.com>,
        davem@davemloft.net, io-uring@vger.kernel.org,
        johannes.berg@intel.com, johannes@sipsolutions.net,
        kuba@kernel.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org,
        netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com,
        viro@zeniv.linux.org.uk
References: <000000000000f3332805b4c330c3@google.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <948d2d3b-5f36-034d-28e6-7490343a5b59@kernel.dk>
Date:   Mon, 23 Nov 2020 09:37:35 -0700
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On 11/23/20 2:55 AM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    27bba9c5 Merge tag 'scsi-fixes' of git://git.kernel.org/pu..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11041f1e500000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=330f3436df12fd44
> dashboard link: https://syzkaller.appspot.com/bug?extid=1f4ba1e5520762c523c6
> compiler:       gcc (GCC) 10.1.0-syz 20200507
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17d9b775500000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=157e4f75500000
> 
> The issue was bisected to:
> 
> commit dcd479e10a0510522a5d88b29b8f79ea3467d501
> Author: Johannes Berg <johannes.berg@intel.com>
> Date:   Fri Oct 9 12:17:11 2020 +0000
> 
>     mac80211: always wind down STA state

Not sure what is going on with the syzbot bisects recently, they are way
off into the weeds...

Anyway, I think the below should fix it.


diff --git a/fs/io_uring.c b/fs/io_uring.c
index 489ec7272b3e..0f2abbff7eec 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7194,9 +7181,9 @@ static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
 	if (!data)
 		return -ENXIO;
 
-	spin_lock(&data->lock);
+	spin_lock_bh(&data->lock);
 	ref_node = data->node;
-	spin_unlock(&data->lock);
+	spin_unlock_bh(&data->lock);
 	if (ref_node)
 		percpu_ref_kill(&ref_node->refs);
 
@@ -7578,7 +7565,7 @@ static void io_file_data_ref_zero(struct percpu_ref *ref)
 	data = ref_node->file_data;
 	ctx = data->ctx;
 
-	spin_lock(&data->lock);
+	spin_lock_bh(&data->lock);
 	ref_node->done = true;
 
 	while (!list_empty(&data->ref_list)) {
@@ -7590,7 +7577,7 @@ static void io_file_data_ref_zero(struct percpu_ref *ref)
 		list_del(&ref_node->node);
 		first_add |= llist_add(&ref_node->llist, &ctx->file_put_llist);
 	}
-	spin_unlock(&data->lock);
+	spin_unlock_bh(&data->lock);
 
 	if (percpu_ref_is_dying(&data->refs))
 		delay = 0;
@@ -7713,9 +7700,9 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
 	}
 
 	file_data->node = ref_node;
-	spin_lock(&file_data->lock);
+	spin_lock_bh(&file_data->lock);
 	list_add_tail(&ref_node->node, &file_data->ref_list);
-	spin_unlock(&file_data->lock);
+	spin_unlock_bh(&file_data->lock);
 	percpu_ref_get(&file_data->refs);
 	return ret;
 out_fput:
@@ -7872,10 +7859,10 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 
 	if (needs_switch) {
 		percpu_ref_kill(&data->node->refs);
-		spin_lock(&data->lock);
+		spin_lock_bh(&data->lock);
 		list_add_tail(&ref_node->node, &data->ref_list);
 		data->node = ref_node;
-		spin_unlock(&data->lock);
+		spin_unlock_bh(&data->lock);
 		percpu_ref_get(&ctx->file_data->refs);
 	} else
 		destroy_fixed_file_ref_node(ref_node);


-- 
Jens Axboe