The patch titled
Subject: mm/memory-failure: send SIGBUS in the event of thp split fail
has been added to the -mm mm-unstable branch. Its filename is
mm-memory-failure-send-sigbus-in-the-event-of-thp-split-fail.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-send-sigbus-in-the-event-of-thp-split-fail.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Jane Chu <jane.chu@xxxxxxxxxx>
Subject: mm/memory-failure: send SIGBUS in the event of thp split fail
Date: Wed, 1 May 2024 17:24:58 -0600
When handle hwpoison in a GUP longterm pin'ed thp page,
try_to_split_thp_page() will fail. And at this point, there is little
else the kernel could do except sending a SIGBUS to the user process, thus
give it a chance to recover.
Link: https://lkml.kernel.org/r/20240501232458.3919593-4-jane.chu@xxxxxxxxxx
Signed-off-by: Jane Chu <jane.chu@xxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Naoya Horiguchi <nao.horiguchi@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory-failure.c | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
--- a/mm/memory-failure.c~mm-memory-failure-send-sigbus-in-the-event-of-thp-split-fail
+++ a/mm/memory-failure.c
@@ -2162,6 +2162,37 @@ out:
return rc;
}
+/*
+ * The calling condition is as such: thp split failed, page might have
+ * been GUP longterm 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 int kill_procs_now(struct page *p, unsigned long pfn, int flags,
+ struct page *hpage)
+{
+ struct folio *folio = page_folio(hpage);
+ LIST_HEAD(tokill);
+ int res = -EHWPOISON;
+
+ /* deal with user pages only */
+ if (PageReserved(p) || PageSlab(p) || PageTable(p) || PageOffline(p))
+ res = -EBUSY;
+ if (!(PageLRU(hpage) || PageHuge(p)))
+ res = -EBUSY;
+
+ if (res == -EHWPOISON) {
+ collect_procs(folio, p, &tokill, flags & MF_ACTION_REQUIRED);
+ kill_procs(&tokill, true, pfn, flags);
+ }
+
+ if (flags & MF_COUNT_INCREASED)
+ put_page(p);
+
+ return res;
+}
+
/**
* memory_failure - Handle memory failure of a page.
* @pfn: Page Number of the corrupted page
@@ -2291,6 +2322,11 @@ try_again:
*/
folio_set_has_hwpoisoned(folio);
if (try_to_split_thp_page(p) < 0) {
+ if (flags & MF_ACTION_REQUIRED) {
+ pr_err("%#lx: thp split failed\n", pfn);
+ res = kill_procs_now(p, pfn, flags, hpage);
+ goto unlock_mutex;
+ }
res = action_result(pfn, MF_MSG_UNSPLIT_THP, MF_IGNORED);
goto unlock_mutex;
}
_
Patches currently in -mm which might be from jane.chu@xxxxxxxxxx are
mm-memory-failure-try-to-send-sigbus-even-if-unmap-failed.patch
mm-madvise-add-mf_action_required-to-madvisemadv_hwpoison.patch
mm-memory-failure-send-sigbus-in-the-event-of-thp-split-fail.patch
