From 37020bbb71d911431e16c2c940b97cf86ae4f2f6 Mon Sep 17 00:00:00 2001 From: Jingbo Xu Date: Mon, 14 Nov 2022 20:19:43 +0800 Subject: [PATCH] erofs: fix missing xas_retry() in fscache mode The xarray iteration only holds the RCU read lock and thus may encounter XA_RETRY_ENTRY if there's process modifying the xarray concurrently. This will cause oops when referring to the invalid entry. Fix this by adding the missing xas_retry(), which will make the iteration wind back to the root node if XA_RETRY_ENTRY is encountered. Fixes: d435d53228dd ("erofs: change to use asynchronous io for fscache readpage/readahead") Suggested-by: David Howells Reviewed-by: Gao Xiang Reviewed-by: Jia Zhu Signed-off-by: Jingbo Xu Link: https://lore.kernel.org/r/20221114121943.29987-1-jefflexu@linux.alibaba.com Signed-off-by: Gao Xiang --- fs/erofs/fscache.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c index 6eaf4a4ab95c..af5ed6b9c54d 100644 --- a/fs/erofs/fscache.c +++ b/fs/erofs/fscache.c @@ -75,11 +75,15 @@ static void erofs_fscache_rreq_unlock_folios(struct netfs_io_request *rreq) rcu_read_lock(); xas_for_each(&xas, folio, last_page) { - unsigned int pgpos = - (folio_index(folio) - start_page) * PAGE_SIZE; - unsigned int pgend = pgpos + folio_size(folio); + unsigned int pgpos, pgend; bool pg_failed = false; + if (xas_retry(&xas, folio)) + continue; + + pgpos = (folio_index(folio) - start_page) * PAGE_SIZE; + pgend = pgpos + folio_size(folio); + for (;;) { if (!subreq) { pg_failed = true;