From: Michal Hocko <mhocko@kernel.org>
To: Mikulas Patocka <mpatocka@redhat.com>
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 18:59:34 +0200 [thread overview]
Message-ID: <20160428165934.GQ31489@dhcp22.suse.cz> (raw)
In-Reply-To: <alpine.LRH.2.02.1604281129360.14065@file01.intranet.prod.int.rdu2.redhat.com>
On Thu 28-04-16 11:40:59, Mikulas Patocka wrote:
[...]
> 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.
It is certainly good to address a common pattern by a helper if it makes
to code easier to follo IMHO.
>
> 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
I have seen this code some time already. I guess it was Al complaining
about it but then I just forgot about it. I have no idea why GFP_ATOMIC
was used there. This predates git times but it should be
https://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.10/2.6.10-mm1/broken-out/alloc_large_system_hash-numa-interleaving.patch
The changelog is quite verbose but no mention about this ugliness.
So I do agree that the above should be fixed and a common helper might
be interesting but I am afraid we are getting off topic here.
Thanks!
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2016-04-28 16:59 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
2016-04-28 16:59 ` Michal Hocko [this message]
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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