Re: [linus:master] [mm] c6307674ed: BUG:sleeping_function_called_from_invalid_context_at_mm/vmalloc.c

[Uladzislau Rezki <urezki@gmail.com>]

Hello, Thomas, Herbert Xu!

> 
> kernel test robot noticed "BUG:sleeping_function_called_from_invalid_context_at_mm/vmalloc.c" on:
> 
> commit: c6307674ed82c0c57d6e1e3408e84ac449ab8e94 ("mm: kvmalloc: add non-blocking support for vmalloc")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> 
> [test failed on linus/master      40286d6379aacfcc053253ef78dc78b09addffda]
> [test failed on linux-next/master 936c21068d7ade00325e40d82bfd2f3f29d9f659]
> 
> in testcase: kunit
> version: 
> with following parameters:
> 
> 	group: group-01
> 
> 
> 
> config: x86_64-rhel-9.4-kunit
> compiler: gcc-14
> test machine: 8 threads 1 sockets Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz (Haswell) with 16G memory
> 
> (please refer to attached dmesg/kmsg for entire log/backtrace)
> 
> 
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <oliver.sang@intel.com>
> | Closes: https://lore.kernel.org/oe-lkp/202604211323.fac1b29e-lkp@intel.com
> 
> 
> 
> [  149.217862][ T4054] BUG: sleeping function called from invalid context at mm/vmalloc.c:3435
> [  149.226291][ T4054] in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 4054, name: rhashtable_thra
> [  149.235634][ T4054] preempt_count: 0, expected: 0
> [  149.240353][ T4054] RCU nest depth: 1, expected: 0
> [  149.245166][ T4054] CPU: 1 UID: 0 PID: 4054 Comm: rhashtable_thra Tainted: G S  B            N  6.18.0-rc5-00047-gc6307674ed82 #1 PREEMPT(voluntary)
> [  149.245176][ T4054] Tainted: [S]=CPU_OUT_OF_SPEC, [B]=BAD_PAGE, [N]=TEST
> [  149.245178][ T4054] Hardware name: Dell Inc. OptiPlex 9020/0DNKMN, BIOS A05 12/05/2013
> [  149.245181][ T4054] Call Trace:
> [  149.245185][ T4054]  <TASK>
> [  149.245189][ T4054]  dump_stack_lvl (lib/dump_stack.c:122)
> [  149.245200][ T4054]  __might_resched.cold (kernel/sched/core.c:8928)
> [  149.245209][ T4054]  vfree (include/linux/kernel.h:61 mm/vmalloc.c:3435)
> [  149.245215][ T4054]  rhashtable_try_insert (lib/rhashtable.c:476 lib/rhashtable.c:635)
> [  149.245223][ T4054]  ? sysvec_apic_timer_interrupt (arch/x86/include/asm/hardirq.h:78 (discriminator 2) arch/x86/kernel/apic/apic.c:1052 (discriminator 2))
> [  149.245229][ T4054]  ? sysvec_apic_timer_interrupt (arch/x86/include/asm/hardirq.h:78 (discriminator 2) arch/x86/kernel/apic/apic.c:1052 (discriminator 2))
> [  149.245235][ T4054]  ? __pfx_rhashtable_try_insert (lib/rhashtable.c:592)
> [  149.245242][ T4054]  rhashtable_insert_slow (lib/rhashtable.c:648)
> [  149.245247][ T4054] insert_retry+0x257/0x630 test_rhashtable
> [  149.245260][ T4054] threadfunc (lib/test_rhashtable.c:633) test_rhashtable
> [  149.245269][ T4054]  ? try_to_wake_up (kernel/sched/core.c:4297)
> [  149.245275][ T4054]  ? _raw_spin_lock_irqsave (arch/x86/include/asm/atomic.h:107 (discriminator 4) include/linux/atomic/atomic-arch-fallback.h:2170 (discriminator 4) include/linux/atomic/atomic-instrumented.h:1302 (discriminator 4) include/asm-generic/qspinlock.h:111 (discriminator 4) include/linux/spinlock.h:187 (discriminator 4) include/linux/spinlock_api_smp.h:111 (discriminator 4) kernel/locking/spinlock.c:162 (discriminator 4))
> [  149.245281][ T4054]  ? __pfx_threadfunc (lib/test_rhashtable.c:618) test_rhashtable
> [  149.245289][ T4054]  ? __pfx_autoremove_wake_function (kernel/sched/wait.c:402)
> [  149.245295][ T4054]  ? __kthread_parkme (arch/x86/include/asm/bitops.h:202 (discriminator 1) arch/x86/include/asm/bitops.h:232 (discriminator 1) include/asm-generic/bitops/instrumented-non-atomic.h:142 (discriminator 1) kernel/kthread.c:290 (discriminator 1))
> [  149.245301][ T4054]  ? __pfx_threadfunc (lib/test_rhashtable.c:618) test_rhashtable
> [  149.245309][ T4054]  ? __pfx_threadfunc (lib/test_rhashtable.c:618) test_rhashtable
> [  149.245317][ T4054]  kthread (kernel/kthread.c:463)
> [  149.245322][ T4054]  ? __pfx_kthread (kernel/kthread.c:412)
> [  149.245326][ T4054]  ? __pfx__raw_spin_lock_irq (kernel/locking/spinlock.c:169)
> [  149.245331][ T4054]  ? __pfx_kthread (kernel/kthread.c:412)
> [  149.245335][ T4054]  ? __pfx_kthread (kernel/kthread.c:412)
> [  149.245339][ T4054]  ret_from_fork (arch/x86/kernel/process.c:164)
> [  149.245344][ T4054]  ? __pfx_kthread (kernel/kthread.c:412)
> [  149.245348][ T4054]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
> [  149.245356][ T4054]  </TASK>
> 
> 
> The kernel config and materials to reproduce are available at:
> https://download.01.org/0day-ci/archive/20260421/202604211323.fac1b29e-lkp@intel.com
> 
> 
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
> 
<snip>
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 6074ed5f66f3..a892766dcedd 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -473,7 +473,7 @@ static int rhashtable_insert_rehash(struct rhashtable *ht,
 
 	err = rhashtable_rehash_attach(ht, tbl, new_tbl);
 	if (err) {
-		bucket_table_free(new_tbl);
+		call_rcu(&new_tbl->rcu, bucket_table_free_rcu);
 		if (err == -EEXIST)
 			err = 0;
 	} else
<snip>

Could you please check? The problem here is

rcu_read_lock()
    rhashtable_insert_rehash()
        vfree();
rcu_read_unlokc();

we can just defer freeing via call_rcu().

--
Uladzislau Rezki