From: Roman Gushchin <guro@fb.com>
To: Wonhyuk Yang <vvghjk1234@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@kernel.org>, <linux-mm@kvack.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Rik van Riel <riel@surriel.com>, Michal Hocko <mhocko@kernel.org>,
<linux-kernel@vger.kernel.org>, <kernel-team@fb.com>
Subject: Re: [PATCH v2 2/2] memblock: do not start bottom-up allocations with kernel_end
Date: Sat, 19 Dec 2020 09:05:35 -0800 [thread overview]
Message-ID: <20201219170535.GA3428478@carbon.DHCP.thefacebook.com> (raw)
In-Reply-To: <CAEcHRTqcrEdXcr02OZnSTgxwQ0Por7y4gAXn6uM=Dp=TVq_5kA@mail.gmail.com>
On Sat, Dec 19, 2020 at 11:52:19PM +0900, Wonhyuk Yang wrote:
> Hi Roman,
>
> On Fri, Dec 18, 2020 at 5:12 AM Roman Gushchin <guro@fb.com> wrote:
> >
> > With kaslr the kernel image is placed at a random place, so starting
> > the bottom-up allocation with the kernel_end can result in an
> > allocation failure and a warning like this one:
> >
> > [ 0.002920] hugetlb_cma: reserve 2048 MiB, up to 2048 MiB per node
> > [ 0.002921] ------------[ cut here ]------------
> > [ 0.002922] memblock: bottom-up allocation failed, memory hotremove may be affected
> > [ 0.002937] WARNING: CPU: 0 PID: 0 at mm/memblock.c:332 memblock_find_in_range_node+0x178/0x25a
> > [ 0.002956] Call Trace:
> > [ 0.002961] ? memblock_alloc_range_nid+0x8d/0x11e
> > [ 0.002963] ? cma_declare_contiguous_nid+0x2c4/0x38c
> > [ 0.002964] ? hugetlb_cma_reserve+0xdc/0x128
> > [ 0.002968] ? flush_tlb_one_kernel+0xc/0x20
> > [ 0.002969] ? native_set_fixmap+0x82/0xd0
> > [ 0.002971] ? flat_get_apic_id+0x5/0x10
> > [ 0.002973] ? register_lapic_address+0x8e/0x97
> > [ 0.002975] ? setup_arch+0x8a5/0xc3f
> > [ 0.002978] ? start_kernel+0x66/0x547
> > [ 0.002980] ? load_ucode_bsp+0x4c/0xcd
> > [ 0.002982] ? secondary_startup_64_no_verify+0xb0/0xbb
> > [ 0.002986] random: get_random_bytes called from __warn+0xab/0x110 with crng_init=0
> >
> > At the same time, the kernel image is protected with memblock_reserve(),
> > so we can just start searching at PAGE_SIZE. In this case the
> > bottom-up allocation has the same chances to success as a top-down
> > allocation, so there is no reason to fallback in the case of a
> > failure. All together it simplifies the logic.
>
> I figure out that it was introduced by
> commit 79442ed189acb ("memblock.c: introduce bottom-up allocation mode")
>
> According to this commit, The purpose of bottom up allocation is to
> allocate memory from the unhotpluggable node.
Hi Wonhyuk,
correct! And it remains this way, we just don't need to skip
all the memory before the kernel_end.
Thanks!
next prev parent reply other threads:[~2020-12-19 17:06 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-17 20:12 [PATCH v2 1/2] mm: cma: allocate cma areas bottom-up Roman Gushchin
2020-12-17 20:12 ` [PATCH v2 2/2] memblock: do not start bottom-up allocations with kernel_end Roman Gushchin
2020-12-19 14:52 ` Wonhyuk Yang
2020-12-19 14:52 ` Wonhyuk Yang
2020-12-19 17:05 ` Roman Gushchin [this message]
2020-12-20 6:49 ` Mike Rapoport
2021-01-22 4:37 ` Thiago Jung Bauermann
2021-01-22 4:37 ` Thiago Jung Bauermann
2021-01-24 2:09 ` Andrew Morton
2021-01-24 2:09 ` Andrew Morton
2021-01-24 7:34 ` Mike Rapoport
2021-01-24 7:34 ` Mike Rapoport
2021-01-26 0:30 ` Thiago Jung Bauermann
2021-01-26 0:30 ` Thiago Jung Bauermann
2021-02-08 23:58 ` Thiago Jung Bauermann
2021-02-08 23:58 ` Thiago Jung Bauermann
2021-02-28 4:18 ` Florian Fainelli
2021-02-28 9:00 ` Mike Rapoport
2021-02-28 18:19 ` Florian Fainelli
2021-02-28 23:08 ` Serge Semin
2021-03-01 3:50 ` Florian Fainelli
2021-03-01 3:50 ` Florian Fainelli
2021-03-01 9:22 ` Serge Semin
2021-03-01 9:22 ` Serge Semin
2021-03-02 4:09 ` Florian Fainelli
2021-03-02 4:09 ` Florian Fainelli
2021-03-02 13:26 ` Serge Semin
2021-03-02 4:19 ` [PATCH] MIPS: BMIPS: Reserve exception base to prevent corruption Florian Fainelli
2021-03-02 8:09 ` Mike Rapoport
2021-03-02 13:54 ` Serge Semin
2021-03-02 19:04 ` Roman Gushchin
2021-03-02 23:54 ` Thomas Bogendoerfer
2021-03-03 1:30 ` Florian Fainelli
2021-03-03 9:41 ` Thomas Bogendoerfer
2021-03-03 17:45 ` Maciej W. Rozycki
2021-03-03 18:15 ` Thomas Bogendoerfer
2021-03-03 21:50 ` Maciej W. Rozycki
2021-03-01 9:45 ` [PATCH v2 2/2] memblock: do not start bottom-up allocations with kernel_end Mike Rapoport
2021-03-01 9:45 ` Mike Rapoport
2021-03-02 3:55 ` Roman Gushchin
2021-03-02 3:55 ` Roman Gushchin
2021-03-02 13:08 ` Serge Semin
2021-03-23 18:19 ` [tip: x86/boot] x86/setup: Consolidate early memory reservations tip-bot2 for Mike Rapoport
2020-12-20 6:48 ` [PATCH v2 1/2] mm: cma: allocate cma areas bottom-up Mike Rapoport
2020-12-21 17:05 ` Roman Gushchin
2020-12-23 4:06 ` Andrew Morton
2020-12-23 16:35 ` Roman Gushchin
2020-12-23 22:10 ` Mike Rapoport
2020-12-28 19:36 ` Roman Gushchin
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=20201219170535.GA3428478@carbon.DHCP.thefacebook.com \
--to=guro@fb.com \
--cc=akpm@linux-foundation.org \
--cc=iamjoonsoo.kim@lge.com \
--cc=kernel-team@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=riel@surriel.com \
--cc=rppt@kernel.org \
--cc=vvghjk1234@gmail.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.