Commit 45711d44 authored by Kairui Song's avatar Kairui Song Committed by Andrew Morton
Browse files

mm, swap: no need to truncate the scan border 

swap_map had a static flexible size, so the last cluster won't be fully
covered, hence the allocator needs to check the scan border to avoid OOB. 
But the swap table has a fixed-sized swap table for each cluster, and the
slots beyond the device size are marked as bad slots.  The allocator can
simply scan all slots as usual, and any bad slots will be skipped.

Link: https://lkml.kernel.org/r/20260218-swap-table-p3-v3-10-f4e34be021a7@tencent.com


Signed-off-by: default avatarKairui Song <kasong@tencent.com>
Acked-by: default avatarChris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 0d6af9bc

mm/swap.h

+1 −1
Original line number Diff line number Diff line
@@ -85,7 +85,7 @@ static inline struct swap_cluster_info *__swap_offset_to_cluster( 
		struct swap_info_struct *si, pgoff_t offset)

{

	VM_WARN_ON_ONCE(percpu_ref_is_zero(&si->users)); /* race with swapoff */

	VM_WARN_ON_ONCE(offset >= si->max);

	VM_WARN_ON_ONCE(offset >= roundup(si->max, SWAPFILE_CLUSTER));

	return &si->cluster_info[offset / SWAPFILE_CLUSTER];

}

mm/swapfile.c

+1 −1
Original line number Diff line number Diff line
@@ -945,8 +945,8 @@ static unsigned int alloc_swap_scan_cluster(struct swap_info_struct *si, 
{

	unsigned int next = SWAP_ENTRY_INVALID, found = SWAP_ENTRY_INVALID;

	unsigned long start = ALIGN_DOWN(offset, SWAPFILE_CLUSTER);

	unsigned long end = min(start + SWAPFILE_CLUSTER, si->max);

	unsigned int order = likely(folio) ? folio_order(folio) : 0;

	unsigned long end = start + SWAPFILE_CLUSTER;

	unsigned int nr_pages = 1 << order;

	bool need_reclaim, ret, usable;