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mm/memory-failure: improve large block size folio handling

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Large block size (LBS) folios cannot be split to order-0 folios but
min_order_for_folio().  Current split fails directly, but that is not
optimal.  Split the folio to min_order_for_folio(), so that, after split,
only the folio containing the poisoned page becomes unusable instead.

For soft offline, do not split the large folio if its
min_order_for_folio() is not 0.  Since the folio is still accessible from
userspace and premature split might lead to potential performance loss.

Link: https://lkml.kernel.org/r/20251031162001.670503-3-ziy@nvidia.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Suggested-by: Jane Chu <jane.chu@oracle.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Pankaj Raghav <kernel@pankajraghav.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Zi Yan 2025-10-31 12:20:00 -04:00 • committed by Andrew Morton
parent a7ef12c64f
commit 689b898677
1 changed files with 27 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

31
mm/memory-failure.c
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@ -1659,12 +1659,13 @@ static int identify_page_state(unsigned long pfn, struct page *p,
* there is still more to do, hence the page refcount we took earlier
* is still needed.
*/
static int try_to_split_thp_page(struct page *page, bool release)
static int try_to_split_thp_page(struct page *page, unsigned int new_order,
bool release)
{
int ret;
lock_page(page);
ret = split_huge_page(page);
ret = split_huge_page_to_order(page, new_order);
unlock_page(page);
if (ret && release)
@ -2420,6 +2421,9 @@ try_again:
folio_unlock(folio);
if (folio_test_large(folio)) {
const int new_order = min_order_for_split(folio);
int err;
/*
* The flag must be set after the refcount is bumped
* otherwise it may race with THP split.
@ -2434,7 +2438,16 @@ try_again:
* page is a valid handlable page.
*/
folio_set_has_hwpoisoned(folio);
if (try_to_split_thp_page(p, false) < 0) {
err = try_to_split_thp_page(p, new_order, /* release= */ false);
/*
* If splitting a folio to order-0 fails, kill the process.
* Split the folio regardless to minimize unusable pages.
* Because the memory failure code cannot handle large
* folios, this split is always treated as if it failed.
*/
if (err || new_order) {
/* get folio again in case the original one is split */
folio = page_folio(p);
res = -EHWPOISON;
kill_procs_now(p, pfn, flags, folio);
put_page(p);
@ -2761,7 +2774,17 @@ static int soft_offline_in_use_page(struct page *page)
};
if (!huge && folio_test_large(folio)) {
if (try_to_split_thp_page(page, true)) {
const int new_order = min_order_for_split(folio);
/*
* If new_order (target split order) is not 0, do not split the
* folio at all to retain the still accessible large folio.
* NOTE: if minimizing the number of soft offline pages is
* preferred, split it to non-zero new_order like it is done in
* memory_failure().
*/
if (new_order || try_to_split_thp_page(page, /* new_order= */ 0,
/* release= */ true)) {
pr_info("%#lx: thp split failed\n", pfn);
return -EBUSY;
}