mm/readahead: limit page cache size in page_cache_ra_order()

In page_cache_ra_order(), the maximal order of the page cache to be
allocated shouldn't be larger than MAX_PAGECACHE_ORDER.  Otherwise, it's
possible the large page cache can't be supported by xarray when the
corresponding xarray entry is split.

For example, HPAGE_PMD_ORDER is 13 on ARM64 when the base page size is
64KB.  The PMD-sized page cache can't be supported by xarray.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 793917d997df ("mm/readahead: Add large folio readahead")
Signed-off-by: Gavin Shan <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Darrick J. Wong <[email protected]>
Cc: Don Dutile <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: William Kucharski <[email protected]>
Cc: Zhenyu Zhang <[email protected]>
Cc: <[email protected]>	[5.18+]
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions