mm/memory-failure: remove obsolete MF_MSG_DIFFERENT_COMPOUND

The page cannot become compound pages again just after a folio is split as an extra refcnt is held. So the MF_MSG_DIFFERENT_COMPOUND case is obsolete and can be removed to get rid of this false assumption and code burden. But add one WARN_ON() here to keep the situation clear. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Miaohe Lin <[email protected]> Cc: Borislav Petkov (AMD) <[email protected]> Cc: Naoya Horiguchi <[email protected]> Cc: Tony Luck <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
chewitt · Jul 12, 2024 · 8a78882 · 8a78882
1 parent a5ea521
commit 8a78882
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Showing 2 changed files with 3 additions and 17 deletions.
diff --git a/include/ras/ras_event.h b/include/ras/ras_event.h
@@ -356,7 +356,6 @@ TRACE_EVENT(aer_event,
 #define MF_PAGE_TYPE		\
 	EM ( MF_MSG_KERNEL, "reserved kernel page" )			\
 	EM ( MF_MSG_KERNEL_HIGH_ORDER, "high-order kernel page" )	\
-	EM ( MF_MSG_DIFFERENT_COMPOUND, "different compound page after locking" ) \
 	EM ( MF_MSG_HUGE, "huge page" )					\
 	EM ( MF_MSG_FREE_HUGE, "free huge page" )			\
 	EM ( MF_MSG_GET_HWPOISON, "get hwpoison page" )			\

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
@@ -919,7 +919,6 @@ static const char *action_name[] = {
 static const char * const action_page_types[] = {
 	[MF_MSG_KERNEL]			= "reserved kernel page",
 	[MF_MSG_KERNEL_HIGH_ORDER]	= "high-order kernel page",
-	[MF_MSG_DIFFERENT_COMPOUND]	= "different compound page after locking",
 	[MF_MSG_HUGE]			= "huge page",
 	[MF_MSG_FREE_HUGE]		= "free huge page",
 	[MF_MSG_GET_HWPOISON]		= "get hwpoison page",
@@ -2349,22 +2348,10 @@ int memory_failure(unsigned long pfn, int flags)
 
 	/*
 	 * We're only intended to deal with the non-Compound page here.
-	 * However, the page could have changed compound pages due to
-	 * race window. If this happens, we could try again to hopefully
-	 * handle the page next round.
+	 * The page cannot become compound pages again as folio has been
+	 * splited and extra refcnt is held.
 	 */
-	if (folio_test_large(folio)) {
-		if (retry) {
-			ClearPageHWPoison(p);
-			folio_unlock(folio);
-			folio_put(folio);
-			flags &= ~MF_COUNT_INCREASED;
-			retry = false;
-			goto try_again;
-		}
-		res = action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
-		goto unlock_page;
-	}
+	WARN_ON(folio_test_large(folio));
 
 	/*
 	 * We use page flags to determine what action should be taken, but