From: Vlastimil Babka <vbabka@suse.cz>
To: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2] mm/kvmalloc: do not call kmalloc for size > KMALLOC_MAX_SIZE
Date: Mon, 5 Nov 2018 17:52:21 +0100 [thread overview]
Message-ID: <af5a1d05-7ee2-b339-1c50-73ae9d66d955@suse.cz> (raw)
In-Reply-To: <d033db53-129d-c031-db78-ba7f9fed5bf4@yandex-team.ru>
On 11/5/18 5:19 PM, Konstantin Khlebnikov wrote:
>
>
> On 05.11.2018 16:03, Vlastimil Babka wrote:
>> On 11/1/18 11:09 AM, Konstantin Khlebnikov wrote:
>>> Allocations over KMALLOC_MAX_SIZE could be served only by vmalloc.
>>>
>>> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
>>
>> Makes sense regardless of warnings stuff.
>>
>> Acked-by: Vlastimil Babka <vbabka@suse.cz>
>>
>> But it must be moved below the GFP_KERNEL check!
>
> But kmalloc cannot handle it regardless of GFP.
Sure, but that's less problematic than skipping to vmalloc() for
!GFP_KERNEL. Especially for large sizes where it's likely that page
tables might get allocated (with GFP_KERNEL).
> Ok maybe write something like this
>
> if (size > KMALLOC_MAX_SIZE) {
> if (WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL)
> return NULL;
> goto do_vmalloc;
> }
Probably should check also for __GFP_NOWARN.
> or fix that uncertainty right in vmalloc
>
> For now comment in vmalloc declares
>
> * Any use of gfp flags outside of GFP_KERNEL should be consulted
> * with mm people.
Dunno, what does Michal think?
> =)
>
>>
>>> ---
>>> mm/util.c | 4 ++++
>>> 1 file changed, 4 insertions(+)
>>>
>>> diff --git a/mm/util.c b/mm/util.c
>>> index 8bf08b5b5760..f5f04fa22814 100644
>>> --- a/mm/util.c
>>> +++ b/mm/util.c
>>> @@ -392,6 +392,9 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node)
>>> gfp_t kmalloc_flags = flags;
>>> void *ret;
>>>
>>> + if (size > KMALLOC_MAX_SIZE)
>>> + goto fallback;
>>> +
>>> /*
>>> * vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
>>> * so the given set of flags has to be compatible.
>>> @@ -422,6 +425,7 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node)
>>> if (ret || size <= PAGE_SIZE)
>>> return ret;
>>>
>>> +fallback:
>>> return __vmalloc_node_flags_caller(size, node, flags,
>>> __builtin_return_address(0));
>>> }
>>>
>>
next prev parent reply other threads:[~2018-11-05 16:55 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-01 9:12 [PATCH] mm/kvmalloc: do not confuse kmalloc with page order over MAX_ORDER Konstantin Khlebnikov
2018-11-01 9:33 ` Michal Hocko
2018-11-01 10:09 ` [PATCH 2] mm/kvmalloc: do not call kmalloc for size > KMALLOC_MAX_SIZE Konstantin Khlebnikov
2018-11-01 10:24 ` Michal Hocko
2018-11-01 10:48 ` Konstantin Khlebnikov
2018-11-01 12:55 ` Michal Hocko
2018-11-01 16:42 ` Konstantin Khlebnikov
2018-11-01 16:55 ` Michal Hocko
2018-11-05 13:03 ` Vlastimil Babka
2018-11-05 16:19 ` Konstantin Khlebnikov
2018-11-05 16:52 ` Vlastimil Babka [this message]
2018-11-05 16:57 ` Michal Hocko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=af5a1d05-7ee2-b339-1c50-73ae9d66d955@suse.cz \
--to=vbabka@suse.cz \
--cc=akpm@linux-foundation.org \
--cc=khlebnikov@yandex-team.ru \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).