mm/memory-failure.c: remove obsolete comment

With the introduction of mf_mutex, most of memory error handling process
is mutually exclusive, so the in-line comment about subtlety about
double-checking PageHWPoison is no more correct.  So remove it.

Link: https://lkml.kernel.org/r/20220125025601.3054511-1-naoya.horiguchi@linux.devSigned-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Suggested-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory-failure.c

@@ -2150,12 +2150,6 @@ static int __soft_offline_page(struct page *page)
 		.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
 	};
 
-	/*
-	 * Check PageHWPoison again inside page lock because PageHWPoison
-	 * is set by memory_failure() outside page lock. Note that
-	 * memory_failure() also double-checks PageHWPoison inside page lock,
-	 * so there's no race between soft_offline_page() and memory_failure().
-	 */
 	lock_page(page);
 	if (!PageHuge(page))
 		wait_on_page_writeback(page);