[PATCH v2 3/6] ceph: Free page array when ceph_submit_write fails

Sam Edwards
2026-01-07T21:02:12Z

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 (and reset locked_pages) 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, making
failures in ceph_submit_write() recoverable as originally intended.

Fixes: 1551ec61dc55 ("ceph: introduce ceph_submit_write() method")
Cc: stable@vger.kernel.org
Signed-off-by: Sam Edwards <CFSworks@gmail.com>
---
fs/ceph/addr.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 2b722916fb9b..467aa7242b49 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -1466,6 +1466,14 @@ 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_wbc->locked_pages = 0;
+
ceph_osdc_put_request(req);
return -EIO;
}
--
2.51.2