bybrooklyn/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-04-18 14:53:58 -04:00
Code Issues Packages Projects Releases Wiki Activity

bpf: Fix RCU stall in bpf_fd_array_map_clear()

Browse Source 
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:
   <TASK>
   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
   </TASK>

Reviewed-by: Sun Jian <sun.jian.kdev@gmail.com>
Fixes: da765a2f59 ("bpf: Add poke dependency tracking for prog array maps")
Signed-off-by: Sechang Lim <rhkrqnwk98@gmail.com>
Link: https://lore.kernel.org/r/20260407103823.3942156-1-rhkrqnwk98@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Sechang Lim
2026-04-07 10:38:23 +00:00
committed by Alexei Starovoitov
parent ae1a82e511
commit 4406942e65
1 changed files with 3 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
kernel/bpf/arraymap.c
View File

@@ -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,