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Filename Latest commit message Latest commit date
Wei Yang 83af658898 mm, sparse: drop pgdat_resize_lock in sparse_add/remove_one_section()
pgdat_resize_lock is used to protect pgdat's memory region information
like: node_start_pfn, node_present_pages, etc.  While in function
sparse_add/remove_one_section(), pgdat_resize_lock is used to protect
initialization/release of one mem_section.  This looks not proper.

These code paths are currently protected by mem_hotplug_lock currently but
should there ever be any reason for locking at the sparse layer a
dedicated lock should be introduced.

Following is the current call trace of sparse_add/remove_one_section()

    mem_hotplug_begin()
    arch_add_memory()
       add_pages()
           __add_pages()
               __add_section()
                   sparse_add_one_section()
    mem_hotplug_done()

    mem_hotplug_begin()
    arch_remove_memory()
        __remove_pages()
            __remove_section()
                sparse_remove_one_section()
    mem_hotplug_done()

The comment above the pgdat_resize_lock also mentions "Holding this will
also guarantee that any pfn_valid() stays that way.", which is true with
the current implementation and false after this patch.  But current
implementation doesn't meet this comment.  There isn't any pfn walkers to
take the lock so this looks like a relict from the past.  This patch also
removes this comment.

[richard.weiyang@gmail.com: v4]
  Link: http://lkml.kernel.org/r/20181204085657.20472-1-richard.weiyang@gmail.com
[mhocko@suse.com: changelog suggestion]
Link: http://lkml.kernel.org/r/20181128091243.19249-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 12:11:49 -08:00
arch mm/memblock.c: skip kmemleak for kasan_init() 2018-12-28 12:11:49 -08:00
block
certs
crypto
Documentation zram: writeback throttle 2018-12-28 12:11:49 -08:00
drivers zram: writeback throttle 2018-12-28 12:11:49 -08:00
firmware
fs userfaultfd: convert userfaultfd_ctx::refcount to refcount_t 2018-12-28 12:11:47 -08:00
include mm, sparse: drop pgdat_resize_lock in sparse_add/remove_one_section() 2018-12-28 12:11:49 -08:00
init
ipc
kernel kernel, resource: check for IORESOURCE_SYSRAM in release_mem_region_adjustable 2018-12-28 12:11:49 -08:00
lib
LICENSES
mm mm, sparse: drop pgdat_resize_lock in sparse_add/remove_one_section() 2018-12-28 12:11:49 -08:00
net mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
samples
scripts
security mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
sound
tools mm, devm_memremap_pages: fix shutdown handling 2018-12-28 12:11:47 -08:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
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Kconfig
MAINTAINERS
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README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.