Commit 1a3798de authored by Jane Chu's avatar Jane Chu Committed by Andrew Morton
Browse files

mm/memory-failure: send SIGBUS in the event of thp split fail 

While handling hwpoison in a THP page, it is possible that
try_to_split_thp_page() fails.  For example, when the THP page has been
RDMA pinned.  At this point, the kernel cannot isolate the poisoned THP
page, all it could do is to send a SIGBUS to the user process with
meaningful payload to give user-level recovery a chance.

Link: https://lkml.kernel.org/r/20240524215306.2705454-6-jane.chu@oracle.com


Signed-off-by: default avatarJane Chu <jane.chu@oracle.com>
Reviewed-by: default avatarOscar Salvador <osalvador@suse.de>
Acked-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <oalvador@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 9b0ab153

mm/memory-failure.c

+29 −5
Original line number Diff line number Diff line
@@ -1706,7 +1706,12 @@ static int identify_page_state(unsigned long pfn, struct page *p, 
	return page_action(ps, p, pfn);

}



static int try_to_split_thp_page(struct page *page)

/*

 * When 'release' is 'false', it means that if thp split has failed,

 * 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)

{

	int ret;
@@ -1714,7 +1719,7 @@ static int try_to_split_thp_page(struct page *page) 
	ret = split_huge_page(page);

	unlock_page(page);



	if (unlikely(ret))

	if (ret && release)

		put_page(page);



	return ret;
@@ -2186,6 +2191,22 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags, 
	return rc;

}



/*

 * The calling condition is as such: thp split failed, page might have

 * been RDMA pinned, not much can be done for recovery.

 * But a SIGBUS should be delivered with vaddr provided so that the user

 * application has a chance to recover. Also, application processes'

 * election for MCE early killed will be honored.

 */

static void kill_procs_now(struct page *p, unsigned long pfn, int flags,

				struct folio *folio)

{

	LIST_HEAD(tokill);



	collect_procs(folio, p, &tokill, flags & MF_ACTION_REQUIRED);

	kill_procs(&tokill, true, pfn, flags);

}



/**

 * memory_failure - Handle memory failure of a page.

 * @pfn: Page Number of the corrupted page
@@ -2327,8 +2348,11 @@ int memory_failure(unsigned long pfn, int flags) 
		 * page is a valid handlable page.

		 */

		folio_set_has_hwpoisoned(folio);

		if (try_to_split_thp_page(p) < 0) {

			res = action_result(pfn, MF_MSG_UNSPLIT_THP, MF_IGNORED);

		if (try_to_split_thp_page(p, false) < 0) {

			res = -EHWPOISON;

			kill_procs_now(p, pfn, flags, folio);

			put_page(p);

			action_result(pfn, MF_MSG_UNSPLIT_THP, MF_FAILED);

			goto unlock_mutex;

		}

		VM_BUG_ON_PAGE(!page_count(p), p);
@@ -2709,7 +2733,7 @@ static int soft_offline_in_use_page(struct page *page) 
	};



	if (!huge && folio_test_large(folio)) {

		if (try_to_split_thp_page(page)) {

		if (try_to_split_thp_page(page, true)) {

			pr_info("soft offline: %#lx: thp split failed\n", pfn);

			return -EBUSY;

		}