linux-mm.kvack.org archive mirror
 help / color / mirror / Atom feed
From: Yang Shi <yang.shi@linaro.org>
To: akpm@linux-foundation.org, mhocko@kernel.org
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linaro-kernel@lists.linaro.org, yang.shi@linaro.org
Subject: [v2 PATCH] mm: make CONFIG_DEFERRED_STRUCT_PAGE_INIT depends on !FLATMEM explicitly
Date: Mon, 23 May 2016 11:15:56 -0700	[thread overview]
Message-ID: <1464027356-32282-1-git-send-email-yang.shi@linaro.org> (raw)

Per the suggestion from Michal Hocko [1], DEFERRED_STRUCT_PAGE_INIT requires
some ordering wrt other initialization operations, e.g. page_ext_init has to
happen after the whole memmap is initialized properly. For SPARSEMEM this
requires to wait for page_alloc_init_late. Other memory models (e.g. flatmem)
might have different initialization layouts (page_ext_init_flatmem). Currently
DEFERRED_STRUCT_PAGE_INIT depends on MEMORY_HOTPLUG which in turn
	depends on SPARSEMEM || X86_64_ACPI_NUMA
	depends on ARCH_ENABLE_MEMORY_HOTPLUG

and X86_64_ACPI_NUMA depends on NUMA which in turn disable FLATMEM
memory model:
config ARCH_FLATMEM_ENABLE
	def_bool y
	depends on X86_32 && !NUMA

so FLATMEM is ruled out via dependency maze. Be explicit and disable
FLATMEM for DEFERRED_STRUCT_PAGE_INIT so that we do not reintroduce
subtle initialization bugs

[1] http://lkml.kernel.org/r/20160523073157.GD2278@dhcp22.suse.cz

CC: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Yang Shi <yang.shi@linaro.org>
---
v2:
 Adopted Michal's comments for the commit log

 mm/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/Kconfig b/mm/Kconfig
index 2664c11..22fa818 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -649,6 +649,7 @@ config DEFERRED_STRUCT_PAGE_INIT
 	default n
 	depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
 	depends on MEMORY_HOTPLUG
+	depends on !FLATMEM
 	help
 	  Ordinarily all struct pages are initialised during early boot in a
 	  single thread. On very large machines this can take a considerable
-- 
2.0.2

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

                 reply	other threads:[~2016-05-23 18:43 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

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=1464027356-32282-1-git-send-email-yang.shi@linaro.org \
    --to=yang.shi@linaro.org \
    --cc=akpm@linux-foundation.org \
    --cc=linaro-kernel@lists.linaro.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@kernel.org \
    /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).