From: Michal Hocko <mhocko@kernel.org>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: trivial@kernel.org, akpm@linux-foundation.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH V2 2/2] mm/memblock.c: check return value of memblock_reserve() in memblock_virt_alloc_internal()
Date: Wed, 21 Dec 2016 08:51:16 +0100 [thread overview]
Message-ID: <20161221075115.GE16502@dhcp22.suse.cz> (raw)
In-Reply-To: <20161220164823.GB13224@vultr.guest>
On Tue 20-12-16 16:48:23, Wei Yang wrote:
> On Mon, Dec 19, 2016 at 04:21:57PM +0100, Michal Hocko wrote:
> >On Sun 18-12-16 14:47:50, Wei Yang wrote:
> >> memblock_reserve() may fail in case there is not enough regions.
> >
> >Have you seen this happenning in the real setups or this is a by-review
> >driven change?
>
> This is a by-review driven change.
>
> >[...]
> >> again:
> >> alloc = memblock_find_in_range_node(size, align, min_addr, max_addr,
> >> nid, flags);
> >> - if (alloc)
> >> + if (alloc && !memblock_reserve(alloc, size))
> >> goto done;
So how exactly does the reserve fail when memblock_find_in_range_node
found a suitable range for the given size?
> >>
> >> if (nid != NUMA_NO_NODE) {
> >> alloc = memblock_find_in_range_node(size, align, min_addr,
> >> max_addr, NUMA_NO_NODE,
> >> flags);
> >> - if (alloc)
> >> + if (alloc && !memblock_reserve(alloc, size))
> >> goto done;
> >> }
> >
> >This doesn't look right. You can end up leaking the first allocated
> >range.
> >
>
> Hmm... why?
>
> If first memblock_reserve() succeed, it will jump to done, so that no 2nd
> allocation.
> If the second executes, it means the first allocation failed.
> memblock_find_in_range_node() doesn't modify the memblock, it just tell you
> there is a proper memory region available.
yes, my bad. I have missed this. Sorry about the confusion.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2016-12-21 7:51 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-18 14:47 [PATCH V2 0/2] mm/memblock.c: fix potential bug and code refine Wei Yang
2016-12-18 14:47 ` [PATCH V2 1/2] mm/memblock.c: trivial code refine in memblock_is_region_memory() Wei Yang
2016-12-19 15:15 ` Michal Hocko
2016-12-20 16:35 ` Wei Yang
2016-12-21 7:48 ` Michal Hocko
2016-12-21 12:43 ` Wei Yang
2016-12-21 12:48 ` Michal Hocko
2016-12-21 13:15 ` Wei Yang
2016-12-18 14:47 ` [PATCH V2 2/2] mm/memblock.c: check return value of memblock_reserve() in memblock_virt_alloc_internal() Wei Yang
2016-12-19 15:21 ` Michal Hocko
2016-12-20 16:48 ` Wei Yang
2016-12-21 7:51 ` Michal Hocko [this message]
2016-12-21 13:13 ` Wei Yang
2016-12-21 13:22 ` Michal Hocko
2016-12-21 14:39 ` Wei Yang
2016-12-21 14:52 ` Michal Hocko
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