From: Uladzislau Rezki <urezki@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Uladzislau Rezki <urezki@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Daniel Wagner <dwagner@suse.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Thomas Gleixner <tglx@linutronix.de>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Hillf Danton <hdanton@sina.com>, Michal Hocko <mhocko@suse.com>,
Matthew Wilcox <willy@infradead.org>,
Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Subject: Re: [PATCH 1/1] mm/vmalloc: remove preempt_disable/enable when do preloading
Date: Mon, 14 Oct 2019 16:27:19 +0200 [thread overview]
Message-ID: <20191014142719.GA17874@pc636> (raw)
In-Reply-To: <20191011165515.a25e7d1c22e6b5e3e6fb69da@linux-foundation.org>
On Fri, Oct 11, 2019 at 04:55:15PM -0700, Andrew Morton wrote:
> On Thu, 10 Oct 2019 17:17:49 +0200 Uladzislau Rezki <urezki@gmail.com> wrote:
>
> > > > : * The preload is done in non-atomic context, thus it allows us
> > > > : * to use more permissive allocation masks to be more stable under
> > > > : * low memory condition and high memory pressure.
> > > > : *
> > > > : * Even if it fails we do not really care about that. Just proceed
> > > > : * as it is. "overflow" path will refill the cache we allocate from.
> > > > : */
> > > > : if (!this_cpu_read(ne_fit_preload_node)) {
> > > >
> > > > Readability nit: local `pva' should be defined here, rather than having
> > > > function-wide scope.
> > > >
> > > > : pva = kmem_cache_alloc_node(vmap_area_cachep, GFP_KERNEL, node);
> > > >
> > > > Why doesn't this honour gfp_mask? If it's not a bug, please add
> > > > comment explaining this.
> > > >
> > But there is a comment, if understand you correctly:
> >
> > <snip>
> > * Even if it fails we do not really care about that. Just proceed
> > * as it is. "overflow" path will refill the cache we allocate from.
> > <snip>
>
> My point is that the alloc_vmap_area() caller passed us a gfp_t but
> this code ignores it, as does adjust_va_to_fit_type(). These *look*
> like potential bugs. If not, they should be commented so they don't
> look like bugs any more ;)
>
I got it, there was misunderstanding from my side :) I agree.
In the first case i should have used and respect the passed "gfp_mask",
like below:
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index f48cd0711478..880b6e8cdeae 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1113,7 +1113,8 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
* Just proceed as it is. If needed "overflow" path
* will refill the cache we allocate from.
*/
- pva = kmem_cache_alloc_node(vmap_area_cachep, GFP_KERNEL, node);
+ pva = kmem_cache_alloc_node(vmap_area_cachep,
+ gfp_mask & GFP_RECLAIM_MASK, node);
spin_lock(&vmap_area_lock);
It should be sent as a separate patch, i think.
As for adjust_va_to_fit_type(), i can add a comment, since we can not
sleep there and the case is one per 1000000 or even lower with your proposal.
Does it sound good?
Thank you!
--
Vlad Rezki
next prev parent reply other threads:[~2019-10-14 14:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-09 16:49 [PATCH 1/1] mm/vmalloc: remove preempt_disable/enable when do preloading Uladzislau Rezki (Sony)
2019-10-09 18:21 ` Steven Rostedt
2019-10-09 22:19 ` Andrew Morton
2019-10-10 2:17 ` Steven Rostedt
2019-10-10 15:17 ` Uladzislau Rezki
2019-10-11 23:55 ` Andrew Morton
2019-10-14 14:27 ` Uladzislau Rezki [this message]
2019-10-14 16:30 ` Michal Hocko
2019-10-15 9:54 ` Uladzislau Rezki
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