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From: Catalin Marinas <catalin.marinas@arm.com>
To: Qian Cai <cai@lca.pw>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Michal Hocko <mhocko@kernel.org>,
	Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v2] mm: kmemleak: Use mempool allocations for kmemleak objects
Date: Wed, 31 Jul 2019 10:53:56 +0100	[thread overview]
Message-ID: <20190731095355.GC63307@arrakis.emea.arm.com> (raw)
In-Reply-To: <1564518157.11067.34.camel@lca.pw>

On Tue, Jul 30, 2019 at 04:22:37PM -0400, Qian Cai wrote:
> On Tue, 2019-07-30 at 12:57 -0700, Andrew Morton wrote:
> > On Sat, 27 Jul 2019 14:23:33 +0100 Catalin Marinas <catalin.marinas@arm.com>
> > > --- a/Documentation/admin-guide/kernel-parameters.txt
> > > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > > @@ -2011,6 +2011,12 @@
> > >  			Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
> > >  			the default is off.
> > >  
> > > +	kmemleak.mempool=
> > > +			[KNL] Boot-time tuning of the minimum kmemleak
> > > +			metadata pool size.
> > > +			Format: <int>
> > > +			Default: NR_CPUS * 4
> > > +
> 
> Catalin, BTW, it is right now unable to handle a large size. I tried to reserve
> 64M (kmemleak.mempool=67108864),
> 
> [    0.039254][    T0] WARNING: CPU: 0 PID: 0 at mm/page_alloc.c:4707 __alloc_pages_nodemask+0x3b8/0x1780
[...]
> [    0.039646][    T0] NIP [c000000000395038] __alloc_pages_nodemask+0x3b8/0x1780
> [    0.039693][    T0] LR [c0000000003d9320] kmalloc_large_node+0x100/0x1a0
> [    0.039727][    T0] Call Trace:
> [    0.039795][    T0] [c00000000170fc80] [c0000000003e5080] __kmalloc_node+0x520/0x890
> [    0.039816][    T0] [c00000000170fd20] [c0000000002e9544] mempool_init_node+0xb4/0x1e0
> [    0.039836][    T0] [c00000000170fd80] [c0000000002e975c] mempool_create_node+0xcc/0x150
> [    0.039857][    T0] [c00000000170fdf0] [c000000000b2a730] kmemleak_init+0x16c/0x54c
> [    0.039878][    T0] [c00000000170fef0] [c000000000ae460c] start_kernel+0x69c/0x7cc
> [    0.039908][    T0] [c00000000170ff90] [c00000000000a7d4] start_here_common+0x1c/0x434
[...]
> [    0.040100][    T0] kmemleak: Kernel memory leak detector disabled

It looks like the mempool cannot be created. 64M objects means a
kmalloc(512MB) for the pool array in mempool_init_node(), so that hits
the MAX_ORDER warning in __alloc_pages_nodemask().

Maybe the mempool tunable won't help much for your case if you need so
many objects. It's still worth having a mempool for kmemleak but we
could look into changing the refill logic while keeping the original
size constant (say 1024 objects).

> [   16.192449][    T1] BUG: Unable to handle kernel data access at 0xffffffffffffb2aa

This doesn't seem kmemleak related from the trace.

-- 
Catalin

  parent reply	other threads:[~2019-07-31  9:54 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-27 13:23 [PATCH v2] mm: kmemleak: Use mempool allocations for kmemleak objects Catalin Marinas
2019-07-30 19:57 ` Andrew Morton
2019-07-30 20:22   ` Qian Cai
2019-07-30 20:39     ` Andrew Morton
2019-07-31  9:53     ` Catalin Marinas [this message]
2019-07-31 12:02       ` Qian Cai
2019-07-31 14:48         ` Catalin Marinas
2019-07-31 14:54           ` Qian Cai
2019-07-31  9:06   ` Michal Hocko
2019-07-31  9:17     ` Catalin Marinas
2019-07-30 20:02 ` Andrew Morton
2019-07-31 15:44   ` Catalin Marinas
2019-08-01  6:41     ` Michal Hocko
2019-08-03 10:48       ` Catalin Marinas
2019-07-31  9:10 ` Michal Hocko

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