From: Sechang Lim Date: Tue, 7 Apr 2026 10:38:23 +0000 (+0000) Subject: bpf: Fix RCU stall in bpf_fd_array_map_clear() X-Git-Tag: v7.1-rc1~174^2~18 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=4406942e65ca128c56c67443832988873c21d2e9;p=thirdparty%2Fkernel%2Flinux.git bpf: Fix RCU stall in bpf_fd_array_map_clear() Add a missing cond_resched() in bpf_fd_array_map_clear() loop. For PROG_ARRAY maps with many entries this loop calls prog_array_map_poke_run() per entry which can be expensive, and without yielding this can cause RCU stalls under load: rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 30932 Comm: kworker/0:2 Not tainted 6.14.0-13195-g967e8def1100 #2 PREEMPT(undef) Workqueue: events prog_array_map_clear_deferred RIP: 0010:write_comp_data+0x38/0x90 kernel/kcov.c:246 Call Trace: prog_array_map_poke_run+0x77/0x380 kernel/bpf/arraymap.c:1096 __fd_array_map_delete_elem+0x197/0x310 kernel/bpf/arraymap.c:925 bpf_fd_array_map_clear kernel/bpf/arraymap.c:1000 [inline] prog_array_map_clear_deferred+0x119/0x1b0 kernel/bpf/arraymap.c:1141 process_one_work+0x898/0x19d0 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x770/0x10b0 kernel/workqueue.c:3400 kthread+0x465/0x880 kernel/kthread.c:464 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x19/0x30 arch/x86/entry/entry_64.S:245 Reviewed-by: Sun Jian Fixes: da765a2f5993 ("bpf: Add poke dependency tracking for prog array maps") Signed-off-by: Sechang Lim Link: https://lore.kernel.org/r/20260407103823.3942156-1-rhkrqnwk98@gmail.com Signed-off-by: Alexei Starovoitov --- diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 33de68c95ad8c..5e25e03535094 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -1015,8 +1015,10 @@ static void bpf_fd_array_map_clear(struct bpf_map *map, bool need_defer) struct bpf_array *array = container_of(map, struct bpf_array, map); int i; - for (i = 0; i < array->map.max_entries; i++) + for (i = 0; i < array->map.max_entries; i++) { __fd_array_map_delete_elem(map, &i, need_defer); + cond_resched(); + } } static void prog_array_map_seq_show_elem(struct bpf_map *map, void *key,