Re: [PATCH -next] mm/kmemleak: move the initialisation of object to __link_object

[Liu Shixin]

On 2023/11/15 0:21, Geert Uytterhoeven wrote:
> Hi Liu,
>
> On Mon, Oct 23, 2023 at 3:52 AM Liu Shixin <liushixin2@xxxxxxxxxx> wrote:
>> Leave __alloc_object() just do the actual allocation and __link_object()
>> do the full initialisation.
>>
>> Suggested-by: Catalin Marinas <catalin.marinas@xxxxxxx>
>> Signed-off-by: Liu Shixin <liushixin2@xxxxxxxxxx>
> Thanks for your patch, which is now commit 245245c2fffd0050
> ("mm/kmemleak: move the initialisation of object to __link_object")
> in v6.7-rc1.
>
> I have bisected to this commit the BUG splat below (seen on various
> platforms).  Reverting this commit fixes the issue.
Thanks for the discovery. It looks like that we can't call set_track_prepare() inside kmemleak_lock.
I will revert this patch.

Thanks.
>
>  Memory: 7923468K/8257536K available (9024K kernel code, 5144K rwdata,
> 4088K rodata, 3072K init, 18331K bss, 268532K reserved, 65536K
> cma-reserved)
>  SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
> +
> +=============================
> +[ BUG: Invalid wait context ]
> +6.6.0-rc4-white-hawk-00387-g245245c2fffd #192 Not tainted
> +-----------------------------
> +swapper/0 is trying to lock:
> +ffffffc0814bbed8 (&zone->lock){....}-{3:3}, at: __rmqueue_pcplist+0x4ac/0x53c
> +other info that might help us debug this:
> +context-{5:5}
> +3 locks held by swapper/0:
> + #0: ffffffc0813cd720 (slab_mutex){....}-{4:4}, at:
> kmem_cache_create_usercopy+0xac/0x2e0
> + #1: ffffffc0813d93e8 (kmemleak_lock){....}-{2:2}, at:
> __create_object+0x48/0x98
> + #2: ffffff86bef6cc98 (&pcp->lock){....}-{3:3}, at:
> get_page_from_freelist+0x184/0x7c0
> +stack backtrace:
> +CPU: 0 PID: 0 Comm: swapper Not tainted
> 6.6.0-rc4-white-hawk-00387-g245245c2fffd #192
> +Hardware name: Renesas White Hawk CPU and Breakout boards based on
> r8a779g0 (DT)
> +Call trace:
> + dump_backtrace+0xac/0xe4
> + show_stack+0x14/0x20
> + dump_stack_lvl+0x68/0x94
> + dump_stack+0x14/0x1c
> + __lock_acquire+0x390/0xffc
> + lock_acquire+0x230/0x28c
> + _raw_spin_lock_irqsave+0x54/0x70
> + __rmqueue_pcplist+0x4ac/0x53c
> + get_page_from_freelist+0x2a8/0x7c0
> + __alloc_pages+0xf4/0x9f8
> + __stack_depot_save+0x178/0x3c8
> + stack_depot_save+0x10/0x18
> + set_track_prepare+0x44/0x70
> + __link_object+0xd0/0x220
> + __create_object+0x64/0x98
> + kmemleak_alloc+0x28/0x34
> + slab_post_alloc_hook.constprop.0+0xbc/0xc4
> + kmem_cache_alloc+0xd4/0x158
> + kmem_cache_create_usercopy+0x1c8/0x2e0
> + kmem_cache_create+0x18/0x20
> + kmemleak_init+0x74/0xfc
> + mm_core_init+0x214/0x250
> + start_kernel+0x2cc/0x4ec
> + __primary_switched+0xb4/0xbc
>  trace event string verifier disabled
>  Running RCU self tests
>
> Gr{oetje,eeting}s,
>
>                         Geert
>