Re: [PATCH v1] erofs: use raw_smp_processor_id() to get buffer from global buffer pool

[Gao Xiang]

Hi Sandeep,

On 2024/4/9 05:52, Sandeep Dhavale wrote:

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+27cc650ef45b379df...@syzkaller.appspotmail.com
Fixes: 7a7513292cc6 ("erofs: rename per-CPU buffers to global buffer pool and make 
it configurable")
Signed-off-by: Sandeep Dhavale <dhav...@google.com>

Thanks for catching this, since the original patch is
for next upstream cycle, may I fold this fix in the
original patch?

I will add your credit into the original patch.

Thanks,
Gao Xiang

---
  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)