From: Uladzislau Rezki <urezki@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Mel Gorman <mgorman@suse.de>,
Christoph Hellwig <hch@infradead.org>,
Matthew Wilcox <willy@infradead.org>,
Nicholas Piggin <npiggin@gmail.com>,
Hillf Danton <hdanton@sina.com>, Michal Hocko <mhocko@suse.com>,
Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH v2 1/2] mm/vmalloc: Use batched page requests in bulk-allocator
Date: Wed, 7 Jul 2021 16:49:21 +0200 [thread overview]
Message-ID: <20210707144921.GC1863@pc638.lan> (raw)
In-Reply-To: <20210706132653.8374852963b25989e360d599@linux-foundation.org>
On Tue, Jul 06, 2021 at 01:26:53PM -0700, Andrew Morton wrote:
> On Mon, 5 Jul 2021 19:05:36 +0200 "Uladzislau Rezki (Sony)" <urezki@gmail.com> wrote:
>
> > In case of simultaneous vmalloc allocations, for example it is 1GB and
> > 12 CPUs my system is able to hit "BUG: soft lockup" for !CONFIG_PREEMPT
> > kernel.
> >
> > <snip>
> > ...
> >
> > are obtained, i.e. do batched page requests adding cond_resched() meanwhile
> > to reschedule. Batched value is hard-coded and is 100 pages per call.
> >
> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
>
> Can we please have a Fixes: for this?
>
> Is this fix important enough for 4.14-rcx? I think so...
>
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -2785,10 +2785,32 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
> > * to fails, fallback to a single page allocator that is
> > * more permissive.
> > */
> > - if (!order)
> > - nr_allocated = alloc_pages_bulk_array_node(
> > - gfp, nid, nr_pages, pages);
> > - else
> > + if (!order) {
> > + while (nr_allocated < nr_pages) {
> > + int nr, nr_pages_request;
> > +
> > + /*
> > + * A maximum allowed request is hard-coded and is 100
> > + * pages per call. That is done in order to prevent a
> > + * long preemption off scenario in the bulk-allocator
> > + * so the range is [1:100].
> > + */
> > + nr_pages_request = min(100, (int)(nr_pages - nr_allocated));
>
> Yes, they types are all over the place.
>
> nr_pages: unsigned long
> nr_allocated: unsigned int
> nr, nr_pages_request: int
>
> Can we please choose the most appropriate type and use that
> consistently?
>
Let me think over it to see what i can do.
--
Vlad Rezki
next prev parent reply other threads:[~2021-07-07 14:51 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-05 17:05 [PATCH v2 1/2] mm/vmalloc: Use batched page requests in bulk-allocator Uladzislau Rezki (Sony)
2021-07-05 17:05 ` [PATCH v2 2/2] mm/vmalloc: Remove gfpflags_allow_blocking() check Uladzislau Rezki (Sony)
2021-07-07 8:51 ` Michal Hocko
2021-07-07 14:43 ` Uladzislau Rezki
2021-07-06 20:26 ` [PATCH v2 1/2] mm/vmalloc: Use batched page requests in bulk-allocator Andrew Morton
2021-07-07 8:42 ` Michal Hocko
2021-07-07 14:47 ` Uladzislau Rezki
2021-07-07 14:49 ` Uladzislau Rezki [this message]
2021-07-07 8:50 ` Michal Hocko
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