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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Rik van Riel <riel@surriel.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        Oscar Salvador <osalvador@suse.de>,
        John Hubbard <jhubbard@nvidia.com>,
        Mel Gorman <mgorman@suse.de>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Matthew Wilcox <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Subject: [PATCH 4.9 27/28] mm: invalidate hwpoison page cache page in fault path
Date:   Tue, 19 Jul 2022 13:54:05 +0200
Message-Id: <20220719114458.617197379@linuxfoundation.org>
In-Reply-To: <20220719114455.701304968@linuxfoundation.org>
References: <20220719114455.701304968@linuxfoundation.org>
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From: Rik van Riel <riel@surriel.com>

commit e53ac7374e64dede04d745ff0e70ff5048378d1f upstream.

Sometimes the page offlining code can leave behind a hwpoisoned clean
page cache page.  This can lead to programs being killed over and over
and over again as they fault in the hwpoisoned page, get killed, and
then get re-spawned by whatever wanted to run them.

This is particularly embarrassing when the page was offlined due to
having too many corrected memory errors.  Now we are killing tasks due
to them trying to access memory that probably isn't even corrupted.

This problem can be avoided by invalidating the page from the page fault
handler, which already has a branch for dealing with these kinds of
pages.  With this patch we simply pretend the page fault was successful
if the page was invalidated, return to userspace, incur another page
fault, read in the file from disk (to a new memory page), and then
everything works again.

Link: https://lkml.kernel.org/r/20220212213740.423efcea@imladris.surriel.com
Signed-off-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[sudip: use int instead of vm_fault_t and adjust context]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 mm/memory.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2891,10 +2891,15 @@ static int __do_fault(struct fault_env *
 	}
 
 	if (unlikely(PageHWPoison(vmf.page))) {
-		if (ret & VM_FAULT_LOCKED)
+		int poisonret = VM_FAULT_HWPOISON;
+		if (ret & VM_FAULT_LOCKED) {
+			/* Retry if a clean page was removed from the cache. */
+			if (invalidate_inode_page(vmf.page))
+				poisonret = 0;
 			unlock_page(vmf.page);
+		}
 		put_page(vmf.page);
-		return VM_FAULT_HWPOISON;
+		return poisonret;
 	}
 
 	if (unlikely(!(ret & VM_FAULT_LOCKED)))