linux-kernel - [PATCH 3/5] ceph: Free page array when ceph_submit

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Message-ID: <20251231024316.4643-4-CFSworks@gmail.com>
Date: Tue, 30 Dec 2025 18:43:14 -0800
From: Sam Edwards <cfsworks@...il.com>
To: Xiubo Li <xiubli@...hat.com>,
	Ilya Dryomov <idryomov@...il.com>
Cc: Viacheslav Dubeyko <Slava.Dubeyko@....com>,
	Christian Brauner <brauner@...nel.org>,
	Milind Changire <mchangir@...hat.com>,
	Jeff Layton <jlayton@...nel.org>,
	ceph-devel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Sam Edwards <CFSworks@...il.com>,
	stable@...r.kernel.org
Subject: [PATCH 3/5] ceph: Free page array when ceph_submit_write fails

If `locked_pages` is zero, the page array must not be allocated:
ceph_process_folio_batch() uses `locked_pages` to decide when to
allocate `pages`, and redundant allocations trigger
ceph_allocate_page_array()'s BUG_ON(), resulting in a worker oops (and
writeback stall) or even a kernel panic. Consequently, the main loop in
ceph_writepages_start() assumes that the lifetime of `pages` is confined
to a single iteration.

The ceph_submit_write() function claims ownership of the page array on
success. But failures only redirty/unlock the pages and fail to free the
array, making the failure case in ceph_submit_write() fatal.

Free the page array in ceph_submit_write()'s error-handling 'if' block
so that the caller's invariant (that the array does not outlive the
iteration) is maintained unconditionally, allowing failures in
ceph_submit_write() to be recoverable as originally intended.

Fixes: 1551ec61dc55 ("ceph: introduce ceph_submit_write() method")
Cc: stable@...r.kernel.org
Signed-off-by: Sam Edwards <CFSworks@...il.com>
---
 fs/ceph/addr.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 2b722916fb9b..91cc43950162 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -1466,6 +1466,13 @@ int ceph_submit_write(struct address_space *mapping,
 			unlock_page(page);
 		}

+		if (ceph_wbc->from_pool) {
+			mempool_free(ceph_wbc->pages, ceph_wb_pagevec_pool);
+			ceph_wbc->from_pool = false;
+		} else
+			kfree(ceph_wbc->pages);
+		ceph_wbc->pages = NULL;
+
 		ceph_osdc_put_request(req);
 		return -EIO;
 	}
-- 
2.51.2