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From: Minchan Kim <minchan@kernel.org>
To: Michal Hocko <mhocko@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	hyesoo.yu@samsung.com, david@redhat.com, surenb@google.com,
	pullip.cho@samsung.com, joaodias@google.com, hridya@google.com,
	john.stultz@linaro.org, sumit.semwal@linaro.org,
	linux-media@vger.kernel.org, devicetree@vger.kernel.org,
	hch@infradead.org, robh+dt@kernel.org,
	linaro-mm-sig@lists.linaro.org
Subject: Re: [PATCH v4 1/4] mm: cma: introduce gfp flag in cma_alloc instead of no_warn
Date: Mon, 25 Jan 2021 11:42:34 -0800
Message-ID: <YA8fKgFLuOi/rSez@google.com> (raw)
In-Reply-To: <20210125130701.GF827@dhcp22.suse.cz>

On Mon, Jan 25, 2021 at 02:07:01PM +0100, Michal Hocko wrote:
> On Thu 21-01-21 09:54:59, Minchan Kim wrote:
> > The upcoming patch will introduce __GFP_NORETRY semantic
> > in alloc_contig_range which is a failfast mode of the API.
> > Instead of adding a additional parameter for gfp, replace
> > no_warn with gfp flag.
> > 
> > To keep old behaviors, it follows the rule below.
> > 
> >   no_warn 			gfp_flags
> > 
> >   false         		GFP_KERNEL
> >   true          		GFP_KERNEL|__GFP_NOWARN
> >   gfp & __GFP_NOWARN		GFP_KERNEL | (gfp & __GFP_NOWARN)
> > 
> > Reviewed-by: Suren Baghdasaryan <surenb@google.com>
> > Signed-off-by: Minchan Kim <minchan@kernel.org>
> [...]
> > diff --git a/mm/cma.c b/mm/cma.c
> > index 0ba69cd16aeb..d50627686fec 100644
> > --- a/mm/cma.c
> > +++ b/mm/cma.c
> > @@ -419,13 +419,13 @@ static inline void cma_debug_show_areas(struct cma *cma) { }
> >   * @cma:   Contiguous memory region for which the allocation is performed.
> >   * @count: Requested number of pages.
> >   * @align: Requested alignment of pages (in PAGE_SIZE order).
> > - * @no_warn: Avoid printing message about failed allocation
> > + * @gfp_mask: GFP mask to use during the cma allocation.
> 
> Call out supported gfp flags explicitly. Have a look at kvmalloc_node
> for a guidance.

How about this?


diff --git a/mm/cma.c b/mm/cma.c
index d50627686fec..b94727b694d6 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -423,6 +423,10 @@ static inline void cma_debug_show_areas(struct cma *cma) { }
  *
  * This function allocates part of contiguous memory on specific
  * contiguous memory area.
+ *
+ * For gfp_mask, GFP_KERNEL and __GFP_NORETRY are supported. __GFP_NORETRY
+ * will avoid costly functions(e.g., waiting on page_writeback and locking)
+ * at current implementaion during the page migration.
  */
 struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
                       gfp_t gfp_mask)


  reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-21 17:54 [PATCH v4 0/4] Chunk Heap Support on DMA-HEAP Minchan Kim
2021-01-21 17:54 ` [PATCH v4 1/4] mm: cma: introduce gfp flag in cma_alloc instead of no_warn Minchan Kim
2021-01-21 18:46   ` David Hildenbrand
2021-01-21 18:50   ` Minchan Kim
2021-01-25 13:07   ` Michal Hocko
2021-01-25 19:42     ` Minchan Kim [this message]
2021-01-26  7:38       ` Michal Hocko
2021-01-26 19:12         ` Minchan Kim
2021-01-27 20:21           ` Minchan Kim
2021-01-21 17:55 ` [PATCH v4 2/4] mm: failfast mode with __GFP_NORETRY in alloc_contig_range Minchan Kim
2021-01-25 13:12   ` Michal Hocko
2021-01-25 13:13     ` Michal Hocko
2021-01-25 19:33     ` Minchan Kim
2021-01-26  7:44       ` Michal Hocko
2021-01-26 19:10         ` Minchan Kim
2021-01-27  8:14           ` Michal Hocko
2021-01-27 20:42         ` Minchan Kim
2021-01-28  7:53           ` Michal Hocko
2021-01-28 16:56             ` Minchan Kim
2021-01-21 17:55 ` [PATCH v4 3/4] dt-bindings: reserved-memory: Make DMA-BUF CMA heap DT-configurable Minchan Kim
2021-01-26  7:07   ` John Stultz
2021-01-27 20:25     ` Hridya Valsaraju
2021-02-05 22:55   ` Rob Herring
2021-01-21 17:55 ` [PATCH v4 4/4] dma-buf: heaps: add chunk heap to dmabuf heaps Minchan Kim
2021-01-26  7:07   ` Christoph Hellwig
2021-01-26 19:27     ` Minchan Kim
2021-01-26  7:32   ` John Stultz
2021-01-26 19:24     ` Minchan Kim
2021-01-26  7:46   ` Michal Hocko
2021-01-26 19:25     ` Minchan Kim
2021-01-27  8:09       ` Michal Hocko

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