6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jason Xing kerneljasonxing@gmail.com
[ Upstream commit 43130d02baa137033c25297aaae95fd0edc41654 ]
We noticed the kworker in page_pool_release_retry() was waken up repeatedly and infinitely in production because of the buggy driver causing the inflight less than 0 and warning us in page_pool_inflight()[1].
Since the inflight value goes negative, it means we should not expect the whole page_pool to get back to work normally.
This patch mitigates the adverse effect by not rescheduling the kworker when detecting the inflight negative in page_pool_release_retry().
[1] [Mon Feb 10 20:36:11 2025] ------------[ cut here ]------------ [Mon Feb 10 20:36:11 2025] Negative(-51446) inflight packet-pages ... [Mon Feb 10 20:36:11 2025] Call Trace: [Mon Feb 10 20:36:11 2025] page_pool_release_retry+0x23/0x70 [Mon Feb 10 20:36:11 2025] process_one_work+0x1b1/0x370 [Mon Feb 10 20:36:11 2025] worker_thread+0x37/0x3a0 [Mon Feb 10 20:36:11 2025] kthread+0x11a/0x140 [Mon Feb 10 20:36:11 2025] ? process_one_work+0x370/0x370 [Mon Feb 10 20:36:11 2025] ? __kthread_cancel_work+0x40/0x40 [Mon Feb 10 20:36:11 2025] ret_from_fork+0x35/0x40 [Mon Feb 10 20:36:11 2025] ---[ end trace ebffe800f33e7e34 ]--- Note: before this patch, the above calltrace would flood the dmesg due to repeated reschedule of release_dw kworker.
Signed-off-by: Jason Xing kerneljasonxing@gmail.com Reviewed-by: Mina Almasry almasrymina@google.com Link: https://patch.msgid.link/20250214064250.85987-1-kerneljasonxing@gmail.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/page_pool.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 31f923e7b5c40..2f2f63c8cf4b0 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -865,7 +865,13 @@ static void page_pool_release_retry(struct work_struct *wq) int inflight;
inflight = page_pool_release(pool); - if (!inflight) + /* In rare cases, a driver bug may cause inflight to go negative. + * Don't reschedule release if inflight is 0 or negative. + * - If 0, the page_pool has been destroyed + * - if negative, we will never recover + * in both cases no reschedule is necessary. + */ + if (inflight <= 0) return;
/* Periodic warning */