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...
This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days
------------------------------------------------------ From: Miaohe Lin linmiaohe@huawei.com 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@huawei.com Fixes: bf181c582588 ("mm/hwpoison: fix unpoison_memory()") Signed-off-by: Miaohe 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: Andrew Morton akpm@linux-foundation.org ---
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@huawei.com 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