linux-kernel - [RFC PATCH] mm: truncate: flush lru cache for evicted inode

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Message-Id: <20240614131856.754-1-hdanton@sina.com>
Date: Fri, 14 Jun 2024 21:18:56 +0800
From: Hillf Danton <hdanton@...a.com>
To: linux-mm@...ck.org
Cc: Hugh Dickins <hughd@...gle.com>,
	Matthew Wilcox <willy@...radead.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Jan Kara <jack@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	syzbot+d79afb004be235636ee8@...kaller.appspotmail.com,
	Hillf Danton <hdanton@...a.com>
Subject: [RFC PATCH] mm: truncate: flush lru cache for evicted inode

Flush lru cache to avoid folio->mapping uaf in case of inode teardown.

Reported-and-tested-by: syzbot+d79afb004be235636ee8@...kaller.appspotmail.com
Signed-off-by: Hillf Danton <hdanton@...a.com>
---
Post for comments because lru_add_drain_all() is too haevy a hammer.

--- x/mm/truncate.c
+++ y/mm/truncate.c
@@ -419,6 +419,9 @@ void truncate_inode_pages_range(struct a
 		truncate_folio_batch_exceptionals(mapping, &fbatch, indices);
 		folio_batch_release(&fbatch);
 	}
+
+	if (mapping_exiting(mapping))
+		lru_add_drain_all();
 }
 EXPORT_SYMBOL(truncate_inode_pages_range);
 
--