linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Michal Hocko <mhocko@kernel.org>
To: Qian Cai <cai@lca.pw>
Cc: akpm@linux-foundation.org, Pavel.Tatashin@microsoft.com,
	mingo@kernel.org, hpa@zytor.com, mgorman@techsingularity.net,
	tglx@linutronix.de, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/page_owner: fix for deferred struct page init
Date: Thu, 20 Dec 2018 10:22:02 +0100	[thread overview]
Message-ID: <20181220092202.GD14234@dhcp22.suse.cz> (raw)
In-Reply-To: <20181220060303.38686-1-cai@lca.pw>

On Thu 20-12-18 01:03:03, Qian Cai wrote:
> When booting a system with "page_owner=on",
> 
> start_kernel
>   page_ext_init
>     invoke_init_callbacks
>       init_section_page_ext
>         init_page_owner
>           init_early_allocated_pages
>             init_zones_in_node
>               init_pages_in_zone
>                 lookup_page_ext
>                   page_to_nid
> 
> The issue here is that page_to_nid() will not work since some page
> flags have no node information until later in page_alloc_init_late() due
> to DEFERRED_STRUCT_PAGE_INIT. Hence, it could trigger an out-of-bounds
> access with an invalid nid.
> 
> [    8.666047] UBSAN: Undefined behaviour in ./include/linux/mm.h:1104:50
> [    8.672603] index 7 is out of range for type 'zone [5]'
> 
> Also, kernel will panic since flags were poisoned earlier with,
> 
> CONFIG_DEBUG_VM_PGFLAGS=y
> CONFIG_NODE_NOT_IN_PAGE_FLAGS=n
> 
> start_kernel
>   setup_arch
>     pagetable_init
>       paging_init
>         sparse_init
>           sparse_init_nid
>             memblock_alloc_try_nid_raw
> 
> Although later it tries to set page flags for pages in reserved bootmem
> regions,
> 
> mm_init
>   mem_init
>     memblock_free_all
>       free_low_memory_core_early
>         reserve_bootmem_region
> 
> there could still have some freed pages from the page allocator but yet
> to be initialized due to DEFERRED_STRUCT_PAGE_INIT. It have already been
> dealt with a bit in page_ext_init().

Is there any reason why we cannot postpone page_ext initialization to
after all the memory is initialized?
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2018-12-20  9:22 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1545172285.18411.26.camel@lca.pw>
2018-12-19  1:57 ` [PATCH] mm: skip checking poison pattern for page_to_nid() Qian Cai
2018-12-19 10:20   ` Michal Hocko
2018-12-19 12:46     ` Qian Cai
2018-12-20  6:03       ` [PATCH] mm/page_owner: fix for deferred struct page init Qian Cai
2018-12-20  9:22         ` Michal Hocko [this message]
2018-12-20 18:50           ` [PATCH v2] " Qian Cai
2018-12-20 20:31             ` [PATCH v3] " Qian Cai
2018-12-20 21:00               ` William Kucharski
2018-12-20 21:04                 ` Qian Cai
2019-01-03 11:51               ` Michal Hocko
2019-01-03 16:38                 ` Qian Cai
2019-01-03 16:59                   ` Michal Hocko
2019-01-03 17:38                     ` Qian Cai
2019-01-03 19:07                       ` Michal Hocko
2019-01-03 19:53                         ` Qian Cai
2019-01-03 20:22                           ` Michal Hocko
2019-01-03 22:22                             ` Qian Cai
2019-01-04 13:09                               ` Michal Hocko
2019-01-04 15:01                                 ` Qian Cai
2019-01-04 15:17                                   ` Michal Hocko
2019-01-04 15:25                                     ` Qian Cai
2019-01-04 15:32                                       ` Michal Hocko
2019-01-04 20:18                                         ` Qian Cai
2019-01-07 18:43                                           ` Michal Hocko
2019-01-08  1:53                                             ` Qian Cai
2019-01-08  8:20                                               ` Michal Hocko
2019-01-08 13:19                                                 ` Qian Cai
2019-01-08 22:02                                                   ` Andrew Morton
2019-01-08 22:13                                                     ` Qian Cai
2019-01-08 22:40                                                       ` Michal Hocko
2019-01-09  7:34             ` [PATCH v2] " Michal Hocko
2019-01-15 20:28               ` [PATCH] Revert "mm: use early_pfn_to_nid in page_ext_init" Qian Cai

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=20181220092202.GD14234@dhcp22.suse.cz \
    --to=mhocko@kernel.org \
    --cc=Pavel.Tatashin@microsoft.com \
    --cc=akpm@linux-foundation.org \
    --cc=cai@lca.pw \
    --cc=hpa@zytor.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mgorman@techsingularity.net \
    --cc=mingo@kernel.org \
    --cc=tglx@linutronix.de \
    /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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).