linux-kernel - Re: [PATCH] kasan: Fix sleeping function called from invalid context in PREEMPT

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Message-ID: <YkbFhgN1jZPTMfnS@linutronix.de>
Date:   Fri, 1 Apr 2022 11:27:34 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Zqiang <qiang1.zhang@...el.com>
Cc:     ryabinin.a.a@...il.com, glider@...gle.com, andreyknvl@...il.com,
        dvyukov@...gle.com, akpm@...ux-foundation.org,
        kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org,
        linux-rt-users@...r.kernel.org
Subject: Re: [PATCH] kasan: Fix sleeping function called from invalid context
 in PREEMPT_RT

On 2022-04-01 17:10:06 [+0800], Zqiang wrote:
> BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
> in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 1, name: swapper/0
> preempt_count: 1, expected: 0
> ...........
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.17.1-rt16-yocto-preempt-rt #22
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009),
> BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014
> Call Trace:
> <TASK>
> dump_stack_lvl+0x60/0x8c
> dump_stack+0x10/0x12
>  __might_resched.cold+0x13b/0x173
> rt_spin_lock+0x5b/0xf0
>  ___cache_free+0xa5/0x180
> qlist_free_all+0x7a/0x160
> per_cpu_remove_cache+0x5f/0x70
> smp_call_function_many_cond+0x4c4/0x4f0
> on_each_cpu_cond_mask+0x49/0xc0
> kasan_quarantine_remove_cache+0x54/0xf0
> kasan_cache_shrink+0x9/0x10
> kmem_cache_shrink+0x13/0x20
> acpi_os_purge_cache+0xe/0x20
> acpi_purge_cached_objects+0x21/0x6d
> acpi_initialize_objects+0x15/0x3b
> acpi_init+0x130/0x5ba
> do_one_initcall+0xe5/0x5b0
> kernel_init_freeable+0x34f/0x3ad
> kernel_init+0x1e/0x140
> ret_from_fork+0x22/0x30
> 
> When the kmem_cache_shrink() be called, the IPI was triggered, the
> ___cache_free() is called in IPI interrupt context, the local lock
> or spin lock will be acquired. on PREEMPT_RT kernel, these lock is
> replaced with sleepbale rt spin lock, so the above problem is triggered.
> fix it by migrating the release action from the IPI interrupt context
> to the task context on RT kernel.

I haven't seen that while playing with kasan. Is this new?
Could we fix in a way that we don't involve freeing memory from in-IRQ?
This could trigger a lockdep splat if the local-lock in SLUB is acquired
from in-IRQ context on !PREEMPT_RT.

> Signed-off-by: Zqiang <qiang1.zhang@...el.com>

Sebastian