mm, hwpoison: remove recalculating hpage

mainline inclusion
from linux-v5.10-rc1
commit 1b473bec
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4LE22
CVE: NA

--------------------------------

hpage is never used after try_to_split_thp_page() in memory_failure(), so
we don't have to update hpage.  So let's not recalculate/use hpage.
Signed-off-by: NNaoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: NOscar Salvador <osalvador@suse.de>
Suggested-by: N"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Reviewed-by: NMike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: NMa Wupeng <mawupeng1@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

mm/memory-failure.c

@@ -1333,7 +1333,6 @@ int memory_failure(unsigned long pfn, int flags)
 		}
 		unlock_page(p);
 		VM_BUG_ON_PAGE(!page_count(p), p);
-		hpage = compound_head(p);
 	}
 
 	/*
@@ -1417,11 +1416,8 @@ int memory_failure(unsigned long pfn, int flags)
 	/*
 	 * Now take care of user space mappings.
 	 * Abort on fail: __delete_from_page_cache() assumes unmapped page.
-	 *
-	 * When the raw error page is thp tail page, hpage points to the raw
-	 * page after thp split.
 	 */
-	if (!hwpoison_user_mappings(p, pfn, flags, &hpage)) {
+	if (!hwpoison_user_mappings(p, pfn, flags, &p)) {
 		action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
 		res = -EBUSY;
 		goto unlock_page;