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Date: Mon,  8 Apr 2024 14:52:29 -0700
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Message-ID: <20240408215231.3376659-1-dhavale@google.com>
Subject: [PATCH v1] erofs: use raw_smp_processor_id() to get buffer from
 global buffer pool
From: Sandeep Dhavale <dhavale@google.com>
To: Gao Xiang <xiang@kernel.org>, Chao Yu <chao@kernel.org>, Yue Hu <huyue2@coolpad.com>, 
	Jeffle Xu <jefflexu@linux.alibaba.com>, Sandeep Dhavale <dhavale@google.com>, 
	Chunhai Guo <guochunhai@vivo.com>
Cc: linux-erofs@lists.ozlabs.org, 
	syzbot+27cc650ef45b379dfe5a@syzkaller.appspotmail.com, 
	kernel-team@android.com, linux-kernel@vger.kernel.org
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erofs will decompress in the preemptible context (kworker or per cpu
thread). As smp_processor_id() cannot be used in preemptible contexts,
use raw_smp_processor_id() instead to index into global buffer pool.

Reported-by: syzbot+27cc650ef45b379dfe5a@syzkaller.appspotmail.com
Fixes: 7a7513292cc6 ("erofs: rename per-CPU buffers to global buffer pool and make it configurable")
Signed-off-by: Sandeep Dhavale <dhavale@google.com>
---
 fs/erofs/zutil.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/erofs/zutil.c b/fs/erofs/zutil.c
index b9b99158bb4e..036024bce9f7 100644
--- a/fs/erofs/zutil.c
+++ b/fs/erofs/zutil.c
@@ -30,7 +30,7 @@ static struct shrinker *erofs_shrinker_info;
 
 static unsigned int z_erofs_gbuf_id(void)
 {
-	return smp_processor_id() % z_erofs_gbuf_count;
+	return raw_smp_processor_id() % z_erofs_gbuf_count;
 }
 
 void *z_erofs_get_gbuf(unsigned int requiredpages)
-- 
2.44.0.478.gd926399ef9-goog