linux/mm
Shachar Raindel 4e047f8977 mm: refactor do_wp_page, extract the reuse case
Currently do_wp_page contains 265 code lines.  It also contains 9 goto
statements, of which 5 are targeting labels which are not cleanup
related.  This makes the function extremely difficult to understand.

The following patches are an attempt at breaking the function to its
basic components, and making it easier to understand.

The patches are straight forward function extractions from do_wp_page.
As we extract functions, we remove unneeded parameters and simplify the
code as much as possible.  However, the functionality is supposed to
remain completely unchanged.  The patches also attempt to document the
functionality of each extracted function.  In patch 2, we split the
unlock logic to the contain logic relevant to specific needs of each use
case, instead of having huge number of conditional decisions in a single
unlock flow.

This patch (of 4):

When do_wp_page is ending, in several cases it needs to reuse the existing
page.  This is achieved by making the page table writable, and possibly
updating the page-cache state.

Currently, this logic was "called" by using a goto jump.  This makes
following the control flow of the function harder.  It is also against the
coding style guidelines for using goto.

As the code can easily be refactored into a specialized function, refactor
it out and simplify the code flow in do_wp_page.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Haggai Eran <haggaie@mellanox.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: Michel Lespinasse <walken@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-14 16:49:03 -07:00
..
kasan kasan, module, vmalloc: rework shadow allocation for modules 2015-03-12 18:46:08 -07:00
backing-dev.c Merge branch 'lazytime' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-02-17 16:12:34 -08:00
balloon_compaction.c
bootmem.c
cleancache.c
cma_debug.c mm-cma-allocation-trigger-fix 2015-04-14 16:49:00 -07:00
cma.c mm: cma: allocation trigger 2015-04-14 16:49:00 -07:00
cma.h mm: cma: allocation trigger 2015-04-14 16:49:00 -07:00
compaction.c mm/compaction: enhance compaction finish condition 2015-04-14 16:49:01 -07:00
debug-pagealloc.c
debug.c
dmapool.c
early_ioremap.c
fadvise.c
failslab.c
filemap.c page_writeback: clean up mess around cancel_dirty_page() 2015-04-14 16:49:01 -07:00
frontswap.c
gup.c mm: move mm_populate()-related code to mm/gup.c 2015-04-14 16:49:00 -07:00
highmem.c
huge_memory.c mm: incorporate zero pages into transparent huge pages 2015-04-14 16:49:01 -07:00
hugetlb_cgroup.c
hugetlb.c mm/hugetlb: use pmd_page() in follow_huge_pmd() 2015-04-14 16:48:56 -07:00
hwpoison-inject.c
init-mm.c
internal.h mm/compaction: enhance compaction finish condition 2015-04-14 16:49:01 -07:00
interval_tree.c
Kconfig mm: cma: debugfs interface 2015-04-14 16:49:00 -07:00
Kconfig.debug
kmemcheck.c
kmemleak-test.c
kmemleak.c
ksm.c
list_lru.c
maccess.c
madvise.c
Makefile mm: cma: debugfs interface 2015-04-14 16:49:00 -07:00
memblock.c mm/memblock.c: rename local variable of memblock_type to `type' 2015-04-14 16:49:00 -07:00
memcontrol.c mm: memcontrol: update copyright notice 2015-04-14 16:49:00 -07:00
memory_hotplug.c mm, hotplug: fix concurrent memory hot-add deadlock 2015-04-14 16:49:00 -07:00
memory-failure.c
memory.c mm: refactor do_wp_page, extract the reuse case 2015-04-14 16:49:03 -07:00
mempolicy.c
mempool.c
migrate.c mm/migrate: mark unmap_and_move() "noinline" to avoid ICE in gcc 4.7.3 2015-04-14 16:48:59 -07:00
mincore.c
mlock.c mm: move mm_populate()-related code to mm/gup.c 2015-04-14 16:49:00 -07:00
mm_init.c
mmap.c mm: rename __mlock_vma_pages_range() to populate_vma_page_range() 2015-04-14 16:49:00 -07:00
mmu_context.c
mmu_notifier.c
mmzone.c
mprotect.c mm: numa: preserve PTE write permissions across a NUMA hinting fault 2015-03-25 16:20:31 -07:00
mremap.c fix mremap() vs. ioctx_kill() race 2015-04-06 17:50:59 -04:00
msync.c
nobootmem.c
nommu.c mm/nommu.c: export symbol max_mapnr 2015-03-12 18:46:08 -07:00
oom_kill.c
page_alloc.c mm: completely remove dumping per-cpu lists from show_mem() 2015-04-14 16:49:01 -07:00
page_counter.c
page_ext.c
page_io.c
page_isolation.c mm/page_alloc.c: call kernel_map_pages in unset_migrateype_isolate 2015-03-25 16:20:30 -07:00
page_owner.c
page-writeback.c page_writeback: clean up mess around cancel_dirty_page() 2015-04-14 16:49:01 -07:00
pagewalk.c mm/pagewalk.c: prevent positive return value of walk_page_test() from being passed to callers 2015-03-25 16:20:30 -07:00
percpu-km.c
percpu-vm.c
percpu.c percpu: Fix trivial typos in comments 2015-03-24 13:41:54 -04:00
pgtable-generic.c
process_vm_access.c
quicklist.c
readahead.c
rmap.c mm: fix anon_vma->degree underflow in anon_vma endless growing prevention 2015-03-25 16:20:30 -07:00
shmem.c mm: shmem: check for mapping owner before dereferencing 2015-02-23 10:00:11 -08:00
slab_common.c
slab.c
slab.h
slob.c slob: make slob_alloc_node() static and remove EXPORT_SYMBOL() 2015-04-14 16:48:59 -07:00
slub.c slub: use bool function return values of true/false not 1/0 2015-04-14 16:48:59 -07:00
sparse-vmemmap.c
sparse.c
swap_cgroup.c
swap_state.c
swap.c
swapfile.c
truncate.c page_writeback: clean up mess around cancel_dirty_page() 2015-04-14 16:49:01 -07:00
util.c
vmacache.c
vmalloc.c kasan, module, vmalloc: rework shadow allocation for modules 2015-03-12 18:46:08 -07:00
vmpressure.c
vmscan.c
vmstat.c
workingset.c
zbud.c
zpool.c
zsmalloc.c
zswap.c