From: Laura Abbott <labbott@redhat.com>
To: Christoph Hellwig <hch@infradead.org>,
Gabriel Krisman Bertazi <krisman@collabora.com>
Cc: linux-mm@kvack.org, kernel@collabora.com,
gael.portay@collabora.com, mike.kravetz@oracle.com,
m.szyprowski@samsung.com
Subject: Re: [PATCH 0/6] Improve handling of GFP flags in the CMA allocator
Date: Wed, 27 Feb 2019 16:12:30 -0800 [thread overview]
Message-ID: <878b80c2-93bc-9ffe-7b2a-6fce97f5bb25@redhat.com> (raw)
In-Reply-To: <20190226142941.GA13684@infradead.org>
On 2/26/19 6:29 AM, Christoph Hellwig wrote:
> I don't think this is a good idea. The whole concept of just passing
> random GFP_ flags to dma_alloc_attrs / dma_alloc_coherent can't work,
> given that on many architectures we need to set up new page tables
> to remap the allocated memory, and we can't use arbitrary gfp flags
> for pte allocations.
>
> So instead of trying to pass them further down again we need to instead
> work to fix all callers of dma_alloc_attrs / dma_alloc_coherent
> that don't just pass GFP_KERNEL.
>
What's the expected approach to fix callers? It's not clear how
you would fix the callers for the case that prompted this series
(context correctly used GFP_NOIO but it was not passed to
dma_alloc_coherent)
Thanks,
Laura
next prev parent reply other threads:[~2019-02-28 0:12 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-18 21:07 Gabriel Krisman Bertazi
2019-02-18 21:07 ` [PATCH 1/6] Revert "kernel/dma: remove unsupported gfp_mask parameter from dma_alloc_from_contiguous()" Gabriel Krisman Bertazi
2019-02-18 21:07 ` [PATCH 2/6] Revert "mm/cma: remove unsupported gfp_mask parameter from cma_alloc()" Gabriel Krisman Bertazi
2019-02-18 21:07 ` [PATCH 3/6] cma: Warn about callers requesting unsupported flags Gabriel Krisman Bertazi
2019-02-18 21:07 ` [PATCH 4/6] cma: Add support for GFP_ZERO Gabriel Krisman Bertazi
2019-02-18 21:07 ` [PATCH 5/6] page_isolation: Propagate temporary pageblock isolation error Gabriel Krisman Bertazi
2019-02-18 21:07 ` [PATCH 6/6] cma: Isolate pageblocks speculatively during allocation Gabriel Krisman Bertazi
2019-02-21 12:39 ` [PATCH 0/6] Improve handling of GFP flags in the CMA allocator Vlastimil Babka
2019-02-26 14:29 ` Christoph Hellwig
2019-02-28 0:12 ` Laura Abbott [this message]
2019-02-28 8:46 ` 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=878b80c2-93bc-9ffe-7b2a-6fce97f5bb25@redhat.com \
--to=labbott@redhat.com \
--cc=gael.portay@collabora.com \
--cc=hch@infradead.org \
--cc=kernel@collabora.com \
--cc=krisman@collabora.com \
--cc=linux-mm@kvack.org \
--cc=m.szyprowski@samsung.com \
--cc=mike.kravetz@oracle.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