linux-kernel - [PATCH] erofs: fix PSI memstall accounting

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Message-ID: <20241127085236.3538334-1-hsiangkao@linux.alibaba.com>
Date: Wed, 27 Nov 2024 16:52:36 +0800
From: Gao Xiang <hsiangkao@...ux.alibaba.com>
To: linux-erofs@...ts.ozlabs.org
Cc: LKML <linux-kernel@...r.kernel.org>,
	Gao Xiang <hsiangkao@...ux.alibaba.com>,
	Max Kellermann <max.kellermann@...os.com>
Subject: [PATCH] erofs: fix PSI memstall accounting

Max Kellermann recently reported psi_group_cpu.tasks[NR_MEMSTALL] is
incorrect in 6.11.9 kernel.

I think the root cause of the recent issue is that since the problematic
commit, bio can be NULL so psi_memstall_leave() could be missed in
z_erofs_submit_queue().

Reported-by: Max Kellermann <max.kellermann@...os.com>
Closes: https://lore.kernel.org/r/CAKPOu+8tvSowiJADW2RuKyofL_CSkm_SuyZA7ME5vMLWmL6pqw@mail.gmail.com
Fixes: 9e2f9d34dd12 ("erofs: handle overlapped pclusters out of crafted images properly")
Signed-off-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
---
 fs/erofs/zdata.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 01f147505487..19ef4ff2a134 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1792,9 +1792,9 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f,
 			erofs_fscache_submit_bio(bio);
 		else
 			submit_bio(bio);
-		if (memstall)
-			psi_memstall_leave(&pflags);
 	}
+	if (memstall)
+		psi_memstall_leave(&pflags);
 
 	/*
 	 * although background is preferred, no one is pending for submission.
-- 
2.43.5