5.10-stable review patch. If anyone has any objections, please let me know.
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From: Kent Overstreet kent.overstreet@gmail.com
commit 3644e2d2dda78e21edd8f5415b6d7ab03f5f54f3 upstream.
If iter->count is 0 and iocb->ki_pos is page aligned, this causes nr_pages to be 0.
Then in generic_file_buffered_read_get_pages() find_get_pages_contig() returns 0 - because we asked for 0 pages, so we call generic_file_buffered_read_no_cached_page() which attempts to add a page to the page cache, which fails with -EEXIST, and then we loop. Oops...
Signed-off-by: Kent Overstreet kent.overstreet@gmail.com Reported-by: Jens Axboe axboe@kernel.dk Reviewed-by: Jens Axboe axboe@kernel.dk Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Suraj Jitindar Singh surajjs@amazon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/filemap.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/mm/filemap.c +++ b/mm/filemap.c @@ -2203,6 +2203,9 @@ ssize_t generic_file_buffered_read(struc
if (unlikely(*ppos >= inode->i_sb->s_maxbytes)) return 0; + if (unlikely(!iov_iter_count(iter))) + return 0; + iov_iter_truncate(iter, inode->i_sb->s_maxbytes);
index = *ppos >> PAGE_SHIFT;