From: Mikulas Patocka <mpatocka@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Shaohua Li <shli@kernel.org>,
dm-devel@redhat.com
Subject: Re: [PATCH] md: simplify free_params for kmalloc vs vmalloc fallback
Date: Thu, 28 Apr 2016 11:40:59 -0400 (EDT) [thread overview]
Message-ID: <alpine.LRH.2.02.1604281129360.14065@file01.intranet.prod.int.rdu2.redhat.com> (raw)
In-Reply-To: <20160428152812.GM31489@dhcp22.suse.cz>
On Thu, 28 Apr 2016, Michal Hocko wrote:
> On Thu 28-04-16 11:04:05, Mikulas Patocka wrote:
> > Acked-by: Mikulas Patocka <mpatocka@redhat.com>
>
> Thanks!
>
> > BTW. we could also use kvmalloc to complement kvfree, proposed here:
> > https://www.redhat.com/archives/dm-devel/2015-July/msg00046.html
>
> If there are sufficient users (I haven't checked other than quick git
> grep on KMALLOC_MAX_SIZE
the problem is that kmallocs with large sizes near KMALLOC_MAX_SIZE are
unreliable, they'll randomly fail if memory is too fragmented.
> and there do not seem that many) who are
> sharing the same fallback strategy then why not. But I suspect that some
> would rather fallback earlier and even do not attempt larger than e.g.
> order-1 requests.
> --
> Michal Hocko
> SUSE Labs
There are many users that use one of these patterns:
if (size <= some_threshold)
p = kmalloc(size);
else
p = vmalloc(size);
or
p = kmalloc(size);
if (!p)
p = vmalloc(size);
For example: alloc_fdmem, seq_buf_alloc, setxattr, getxattr, ipc_alloc,
pidlist_allocate, get_pages_array, alloc_bucket_locks,
frame_vector_create. If you grep the kernel for vmalloc, you'll find this
pattern over and over again.
In alloc_large_system_hash, there is
table = __vmalloc(size, GFP_ATOMIC, PAGE_KERNEL);
- that is clearly wrong because __vmalloc doesn't respect GFP_ATOMIC
Mikulas
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next prev parent reply other threads:[~2016-04-28 15:41 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-28 13:23 [PATCH 0/19] get rid of superfluous __GFP_REPEAT Michal Hocko
2016-04-28 13:23 ` [PATCH 01/20] tree wide: get rid of __GFP_REPEAT for order-0 allocations part I Michal Hocko
2016-04-28 13:23 ` [PATCH 02/20] x86: get rid of superfluous __GFP_REPEAT Michal Hocko
2016-04-28 13:23 ` [PATCH 03/20] x86/efi: " Michal Hocko
2016-04-28 13:23 ` [PATCH 04/20] arm: " Michal Hocko
2016-04-28 14:55 ` Russell King - ARM Linux
2016-04-28 15:08 ` Michal Hocko
2016-04-29 9:41 ` Michal Hocko
2016-04-28 13:23 ` [PATCH 05/20] arm64: " Michal Hocko
2016-04-28 13:23 ` [PATCH 06/20] arc: " Michal Hocko
2016-04-28 13:23 ` [PATCH 07/20] mips: " Michal Hocko
2016-04-28 13:23 ` [PATCH 08/20] nios2: " Michal Hocko
2016-04-28 13:23 ` [PATCH 09/20] parisc: " Michal Hocko
2016-04-28 13:23 ` [PATCH 10/20] score: " Michal Hocko
2016-04-28 13:23 ` [PATCH 11/20] powerpc: " Michal Hocko
2016-04-28 13:23 ` [PATCH 12/20] sparc: " Michal Hocko
2016-04-28 13:23 ` [PATCH 13/20] s390: " Michal Hocko
2016-04-28 13:24 ` [PATCH 14/20] sh: " Michal Hocko
2016-04-28 13:24 ` [PATCH 15/20] tile: " Michal Hocko
2016-04-28 16:21 ` Chris Metcalf
2016-04-28 13:24 ` [PATCH 16/20] unicore32: " Michal Hocko
2016-04-28 13:24 ` [PATCH 17/20] dm: get rid of superfluous gfp flags Michal Hocko
2016-04-29 18:54 ` Mike Snitzer
2016-05-02 7:31 ` Michal Hocko
2016-04-28 13:24 ` [PATCH 18/20] dm: clean up GFP_NIO usage Michal Hocko
2016-04-28 14:20 ` Mikulas Patocka
2016-04-28 14:41 ` Michal Hocko
2016-04-28 13:24 ` [PATCH 19/20] md: simplify free_params for kmalloc vs vmalloc fallback Michal Hocko
2016-04-28 14:51 ` [PATCH] " Michal Hocko
2016-04-28 15:04 ` Mikulas Patocka
2016-04-28 15:28 ` Michal Hocko
2016-04-28 15:40 ` Mikulas Patocka [this message]
2016-04-28 16:59 ` Michal Hocko
2016-04-28 15:37 ` [PATCH 19/20] " Mike Snitzer
2016-04-28 16:00 ` Michal Hocko
2016-04-28 13:24 ` [PATCH 20/20] jbd2: get rid of superfluous __GFP_REPEAT Michal Hocko
2016-05-12 16:53 ` [PATCH 0/19] " Michal Hocko
2016-05-12 20:13 ` Andrew Morton
2016-05-13 6:58 ` Michal Hocko
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