Commit f29623e4 authored by Miaohe Lin's avatar Miaohe Lin Committed by Andrew Morton
Browse files

mm: memory-failure: fix potential unexpected return value from unpoison_memory() 

If unpoison_memory() fails to clear page hwpoisoned flag, return value ret
is expected to be -EBUSY.  But when get_hwpoison_page() returns 1 and
fails to clear page hwpoisoned flag due to races, return value will be
unexpected 1 leading to users being confused.  And there's a code smell
that the variable "ret" is used not only to save the return value of
unpoison_memory(), but also the return value from get_hwpoison_page(). 
Make a further cleanup by using another auto-variable solely to save the
return value of get_hwpoison_page() as suggested by Naoya.

Link: https://lkml.kernel.org/r/20230727115643.639741-3-linmiaohe@huawei.com


Fixes: bf181c58 ("mm/hwpoison: fix unpoison_memory()")
Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent f985fc32

mm/memory-failure.c

+9 −10
Original line number Diff line number Diff line
@@ -2466,7 +2466,7 @@ int unpoison_memory(unsigned long pfn) 
{

	struct folio *folio;

	struct page *p;

	int ret = -EBUSY;

	int ret = -EBUSY, ghp;

	unsigned long count = 1;

	bool huge = false;

	static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
@@ -2514,29 +2514,28 @@ int unpoison_memory(unsigned long pfn) 
	if (folio_test_slab(folio) || PageTable(&folio->page) || folio_test_reserved(folio))

		goto unlock_mutex;



	ret = get_hwpoison_page(p, MF_UNPOISON);

	if (!ret) {

	ghp = get_hwpoison_page(p, MF_UNPOISON);

	if (!ghp) {

		if (PageHuge(p)) {

			huge = true;

			count = folio_free_raw_hwp(folio, false);

			if (count == 0) {

				ret = -EBUSY;

			if (count == 0)

				goto unlock_mutex;

		}

		}

		ret = folio_test_clear_hwpoison(folio) ? 0 : -EBUSY;

	} else if (ret < 0) {

		if (ret == -EHWPOISON) {

	} else if (ghp < 0) {

		if (ghp == -EHWPOISON) {

			ret = put_page_back_buddy(p) ? 0 : -EBUSY;

		} else

		} else {

			ret = ghp;

			unpoison_pr_info("Unpoison: failed to grab page %#lx\n",

					 pfn, &unpoison_rs);

		}

	} else {

		if (PageHuge(p)) {

			huge = true;

			count = folio_free_raw_hwp(folio, false);

			if (count == 0) {

				ret = -EBUSY;

				folio_put(folio);

				goto unlock_mutex;

			}