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From: Sasha Levin <sashal@kernel.org>
To: stable@vger.kernel.org,
	tonyb@cybernetics.com
Cc: Greg Edwards <gedwards@ddn.com>,
	Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: FAILED: Patch "block: Fix page refcounts for unaligned buffers in __bio_release_pages()" failed to apply to 6.1-stable tree
Date: Wed, 27 Mar 2024 08:13:29 -0400
Message-ID: <20240327121329.2830355-1-sashal@kernel.org>
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The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From 38b43539d64b2fa020b3b9a752a986769f87f7a6 Mon Sep 17 00:00:00 2001
From: Tony Battersby <tonyb@cybernetics.com>
Date: Thu, 29 Feb 2024 13:08:09 -0500
Subject: [PATCH] block: Fix page refcounts for unaligned buffers in
 __bio_release_pages()

Fix an incorrect number of pages being released for buffers that do not
start at the beginning of a page.

Fixes: 1b151e2435fc ("block: Remove special-casing of compound pages")
Cc: stable@vger.kernel.org
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Tested-by: Greg Edwards <gedwards@ddn.com>
Link: https://lore.kernel.org/r/86e592a9-98d4-4cff-a646-0c0084328356@cybernetics.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/bio.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 496867b51609f..a8b6919400270 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1153,7 +1153,7 @@ void __bio_release_pages(struct bio *bio, bool mark_dirty)
 
 	bio_for_each_folio_all(fi, bio) {
 		struct page *page;
-		size_t done = 0;
+		size_t nr_pages;
 
 		if (mark_dirty) {
 			folio_lock(fi.folio);
@@ -1161,10 +1161,11 @@ void __bio_release_pages(struct bio *bio, bool mark_dirty)
 			folio_unlock(fi.folio);
 		}
 		page = folio_page(fi.folio, fi.offset / PAGE_SIZE);
+		nr_pages = (fi.offset + fi.length - 1) / PAGE_SIZE -
+			   fi.offset / PAGE_SIZE + 1;
 		do {
 			bio_release_page(bio, page++);
-			done += PAGE_SIZE;
-		} while (done < fi.length);
+		} while (--nr_pages != 0);
 	}
 }
 EXPORT_SYMBOL_GPL(__bio_release_pages);
-- 
2.43.0