From: Vlastimil Babka <vbabka@suse.cz>
To: Hyeonggon Yoo <42.hyeyoo@gmail.com>, Guenter Roeck <linux@roeck-us.net>
Cc: Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 10/17] mm/slab: kmalloc: pass requests larger than order-1 page to page allocator
Date: Sat, 15 Oct 2022 21:39:08 +0200 [thread overview]
Message-ID: <7ad9081b-9082-2cbb-5732-f87366dca801@suse.cz> (raw)
In-Reply-To: <Y0n1WxxwbgSOmMwJ@hyeyoo>
On 10/15/22 01:48, Hyeonggon Yoo wrote:
> On Fri, Oct 14, 2022 at 01:58:18PM -0700, Guenter Roeck wrote:
>> Hi,
>>
>> On Wed, Aug 17, 2022 at 07:18:19PM +0900, Hyeonggon Yoo wrote:
>> > There is not much benefit for serving large objects in kmalloc().
>> > Let's pass large requests to page allocator like SLUB for better
>> > maintenance of common code.
>> >
>> > Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
>> > Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
>> > ---
>>
>> This patch results in a WARNING backtrace in all mips and sparc64
>> emulations.
>>
>> ------------[ cut here ]------------
>> WARNING: CPU: 0 PID: 0 at mm/slab_common.c:729 kmalloc_slab+0xc0/0xdc
>> Modules linked in:
>> CPU: 0 PID: 0 Comm: swapper Not tainted 6.0.0-11990-g9c9155a3509a #1
>> Stack : ffffffff 801b2a18 80dd0000 00000004 00000000 00000000 81023cd4 00000000
>> 81040000 811a9930 81040000 8104a628 81101833 00000001 81023c78 00000000
>> 00000000 00000000 80f5d858 81023b98 00000001 00000023 00000000 ffffffff
>> 00000000 00000064 00000002 81040000 81040000 00000001 80f5d858 000002d9
>> 00000000 00000000 80000000 80002000 00000000 00000000 00000000 00000000
>> ...
>> Call Trace:
>> [<8010a2bc>] show_stack+0x38/0x118
>> [<80cf5f7c>] dump_stack_lvl+0xac/0x104
>> [<80130d7c>] __warn+0xe0/0x224
>> [<80cdba5c>] warn_slowpath_fmt+0x64/0xb8
>> [<8028c058>] kmalloc_slab+0xc0/0xdc
>>
>> irq event stamp: 0
>> hardirqs last enabled at (0): [<00000000>] 0x0
>> hardirqs last disabled at (0): [<00000000>] 0x0
>> softirqs last enabled at (0): [<00000000>] 0x0
>> softirqs last disabled at (0): [<00000000>] 0x0
>> ---[ end trace 0000000000000000 ]---
>>
>> Guenter
>
> Hi.
>
> Thank you so much for this report!
>
> Hmm so SLAB tries to find kmalloc cache for freelist index array using
> kmalloc_slab() directly, and it becomes problematic when size of the
> array is larger than PAGE_SIZE * 2.
Hmm interesting, did you find out how exactly that can happen in practice,
or what's special about mips and sparc64 here? Because normally
calculate_slab_order() will only go up to slab_max_order, which AFAICS can
only go up to SLAB_MAX_ORDER_HI, thus 1, unless there's a boot command line
override.
And if we have two pages for objects, surely even with small objects they
can't be smaller than freelist_idx_t, so if the number of objects fits into
two pages (order 1), then the freelist array should also fit in two pages?
Thanks,
Vlastimil
> Will send a fix soon.
>
next prev parent reply other threads:[~2022-10-15 19:39 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-17 10:18 [PATCH v4 00/17] common kmalloc v4 Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 01/17] mm/slab: move NUMA-related code to __do_cache_alloc() Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 02/17] mm/slab: cleanup slab_alloc() and slab_alloc_node() Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 03/17] mm/slab_common: remove CONFIG_NUMA ifdefs for common kmalloc functions Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 04/17] mm/slab_common: cleanup kmalloc_track_caller() Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 05/17] mm/sl[au]b: factor out __do_kmalloc_node() Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 06/17] mm/slab_common: fold kmalloc_order_trace() into kmalloc_large() Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 07/17] mm/slub: move kmalloc_large_node() to slab_common.c Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 08/17] mm/slab_common: kmalloc_node: pass large requests to page allocator Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 09/17] mm/slab_common: cleanup kmalloc_large() Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 10/17] mm/slab: kmalloc: pass requests larger than order-1 page to page allocator Hyeonggon Yoo
2022-10-14 20:58 ` Guenter Roeck
2022-10-14 23:48 ` Hyeonggon Yoo
2022-10-15 19:39 ` Vlastimil Babka [this message]
2022-10-16 9:10 ` Hyeonggon Yoo
2022-10-15 4:34 ` [PATCH] mm/slab: use kmalloc_node() for off slab freelist_idx_t array allocation Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 11/17] mm/sl[au]b: introduce common alloc/free functions without tracepoint Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 12/17] mm/sl[au]b: generalize kmalloc subsystem Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 13/17] mm/sl[au]b: cleanup kmem_cache_alloc[_node]_trace() Hyeonggon Yoo
2022-08-23 15:04 ` Vlastimil Babka
2022-08-24 3:54 ` Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 14/17] mm/slab_common: unify NUMA and UMA version of tracepoints Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 15/17] mm/slab_common: drop kmem_alloc & avoid dereferencing fields when not using Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 16/17] mm/slab_common: move declaration of __ksize() to mm/slab.h Hyeonggon Yoo
2022-08-17 10:18 ` [PATCH v4 17/17] mm/sl[au]b: check if large object is valid in __ksize() Hyeonggon Yoo
2022-08-23 15:12 ` Vlastimil Babka
2022-08-24 3:52 ` Hyeonggon Yoo
2022-08-23 15:16 ` [PATCH v4 00/17] common kmalloc v4 Vlastimil Babka
2022-08-24 3:58 ` Hyeonggon Yoo
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