The patch titled
Subject: mm: memory-failure: fix potential unexpected return value from unpoison_memory()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-memory-failure-fix-potential-unexpected-return-value-from-unpoison_memory.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memory-failure-fix-potential-unexpected-return-value-from-unpoison_memory.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm: memory-failure: fix potential unexpected return value from unpoison_memory()
Date: Thu, 27 Jul 2023 19:56:41 +0800
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@xxxxxxxxxx
Fixes: bf181c582588 ("mm/hwpoison: fix unpoison_memory()")
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory-failure.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
--- a/mm/memory-failure.c~mm-memory-failure-fix-potential-unexpected-return-value-from-unpoison_memory
+++ a/mm/memory-failure.c
@@ -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;
}
_
Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are
mm-swapfile-fix-wrong-swap-entry-type-for-hwpoisoned-swapcache-page.patch
mm-memory-failure-fix-potential-unexpected-return-value-from-unpoison_memory.patch
mm-memory-failure-avoid-false-hwpoison-page-mapped-error-info.patch
mm-memory-failure-add-pageoffline-check.patch
mm-mm_initc-update-obsolete-comment-in-get_pfn_range_for_nid.patch
mm-memory-failure-fix-unexpected-return-value-in-soft_offline_page.patch
mm-memory-failure-fix-potential-page-refcnt-leak-in-memory_failure.patch
mm-memory-failure-remove-unneeded-page-state-check-in-shake_page.patch
memory-tier-use-helper-function-destroy_memory_type.patch
mm-memory-failure-remove-unneeded-inline-annotation.patch
mm-mm_initc-remove-obsolete-macro-hash_small.patch
mm-page_alloc-avoid-false-page-outside-zone-error-info.patch
memory-tier-rename-destroy_memory_type-to-put_memory_type.patch
mm-remove-obsolete-comment-above-struct-per_cpu_pages.patch
mm-memcg-minor-cleanup-for-mem_cgroup_id_max.patch
mm-memory-failure-remove-unneeded-pagehuge-check.patch
mm-memory-failure-ensure-moving-hwpoison-flag-to-the-raw-error-pages.patch
mm-memory-failure-dont-account-hwpoison_filter-filtered-pages.patch
mm-memory-failure-use-local-variable-huge-to-check-hugetlb-page.patch
mm-memory-failure-remove-unneeded-header-files.patch
mm-memory-failure-minor-cleanup-for-comments-and-codestyle.patch
mm-memory-failure-fetch-compound-head-after-extra-page-refcnt-is-held.patch
mm-memory-failure-fix-race-window-when-trying-to-get-hugetlb-folio.patch
mm-huge_memory-use-rmap_none-when-calling-page_add_anon_rmap.patch
mm-memcg-fix-obsolete-comment-above-mem_cgroup_max_reclaim_loops.patch
mm-memcg-minor-cleanup-for-mc_handle_present_pte.patch
memory-tier-use-helper-macro-__attr_rw.patch
mm-fix-obsolete-function-name-above-debug_pagealloc_enabled_static.patch
mm-mprotect-fix-obsolete-function-name-in-change_pte_range.patch
mm-memcg-fix-obsolete-function-name-in-mem_cgroup_protection.patch
