Commit e4aec577 authored by Gavin Shan's avatar Gavin Shan Committed by Liu Shixin
Browse files

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

mainline inclusion
from mainline-v6.10
commit 1f789a45c3f1aa77531db21768fca70b66c0eeb1
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IAHY3K

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1f789a45c3f1aa77531db21768fca70b66c0eeb1

--------------------------------

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/20240627003953.1262512-3-gshan@redhat.com


Fixes: 793917d9 ("mm/readahead: Add large folio readahead")
Signed-off-by: default avatarGavin Shan <gshan@redhat.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Zhenyu Zhang <zhenyzha@redhat.com>
Cc: <stable@vger.kernel.org>	[5.18+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLiu Shixin <liushixin2@huawei.com>
parent 9cd28575

mm/readahead.c

+4 −4
Original line number Diff line number Diff line
@@ -506,11 +506,11 @@ void page_cache_ra_order(struct readahead_control *ractl, 


	limit = min(limit, index + ra->size - 1);



	if (new_order < MAX_PAGECACHE_ORDER) {

	if (new_order < MAX_PAGECACHE_ORDER)

		new_order += 2;



	new_order = min_t(unsigned int, MAX_PAGECACHE_ORDER, new_order);

	new_order = min_t(unsigned int, new_order, ilog2(ra->size));

	}



	/* See comment in page_cache_ra_unbounded() */

	nofs = memalloc_nofs_save();