linux.git/include/linux/mm.h, branch v3.19-rc2

vm_area_operations: kill ->migrate()

2014-12-17T13:26:51+00:00

the only instance this method has ever grown was one in kernfs -
one that call ->migrate() of another vm_ops if it exists.

Signed-off-by: Al Viro

mm: vmscan: invoke slab shrinkers from shrink_zone()

2014-12-13T20:42:48+00:00

The slab shrinkers are currently invoked from the zonelist walkers in
kswapd, direct reclaim, and zone reclaim, all of which roughly gauge the
eligible LRU pages and assemble a nodemask to pass to NUMA-aware
shrinkers, which then again have to walk over the nodemask.  This is
redundant code, extra runtime work, and fairly inaccurate when it comes to
the estimation of actually scannable LRU pages.  The code duplication will
only get worse when making the shrinkers cgroup-aware and requiring them
to have out-of-band cgroup hierarchy walks as well.

Instead, invoke the shrinkers from shrink_zone(), which is where all
reclaimers end up, to avoid this duplication.

Take the count for eligible LRU pages out of get_scan_count(), which
considers many more factors than just the availability of swap space, like
zone_reclaimable_pages() currently does.  Accumulate the number over all
visited lruvecs to get the per-zone value.

Some nodes have multiple zones due to memory addressing restrictions.  To
avoid putting too much pressure on the shrinkers, only invoke them once
for each such node, using the class zone of the allocation as the pivot
zone.

For now, this integrates the slab shrinking better into the reclaim logic
and gets rid of duplicative invocations from kswapd, direct reclaim, and
zone reclaim.  It also prepares for cgroup-awareness, allowing
memcg-capable shrinkers to be added at the lruvec level without much
duplication of both code and runtime work.

This changes kswapd behavior, which used to invoke the shrinkers for each
zone, but with scan ratios gathered from the entire node, resulting in
meaningless pressure quantities on multi-zone nodes.

Zone reclaim behavior also changes.  It used to shrink slabs until the
same amount of pages were shrunk as were reclaimed from the LRUs.  Now it
merely invokes the shrinkers once with the zone's scan ratio, which makes
the shrinkers go easier on caches that implement aging and would prefer
feeding back pressure from recently used slab objects to unused LRU pages.

[vdavydov@parallels.com: assure class zone is populated]
Signed-off-by: Johannes Weiner 
Cc: Dave Chinner 
Signed-off-by: Vladimir Davydov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/debug-pagealloc: make debug-pagealloc boottime configurable

2014-12-13T20:42:48+00:00

Now, we have prepared to avoid using debug-pagealloc in boottime.  So
introduce new kernel-parameter to disable debug-pagealloc in boottime, and
makes related functions to be disabled in this case.

Only non-intuitive part is change of guard page functions.  Because guard
page is effective only if debug-pagealloc is enabled, turning off
according to debug-pagealloc is reasonable thing to do.

Signed-off-by: Joonsoo Kim 
Cc: Mel Gorman 
Cc: Johannes Weiner 
Cc: Minchan Kim 
Cc: Dave Hansen 
Cc: Michal Nazarewicz 
Cc: Jungsoo Son 
Cc: Ingo Molnar 
Cc: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/debug-pagealloc: prepare boottime configurable on/off

2014-12-13T20:42:48+00:00

Until now, debug-pagealloc needs extra flags in struct page, so we need to
recompile whole source code when we decide to use it.  This is really
painful, because it takes some time to recompile and sometimes rebuild is
not possible due to third party module depending on struct page.  So, we
can't use this good feature in many cases.

Now, we have the page extension feature that allows us to insert extra
flags to outside of struct page.  This gets rid of third party module
issue mentioned above.  And, this allows us to determine if we need extra
memory for this page extension in boottime.  With these property, we can
avoid using debug-pagealloc in boottime with low computational overhead in
the kernel built with CONFIG_DEBUG_PAGEALLOC.  This will help our
development process greatly.

This patch is the preparation step to achive above goal.  debug-pagealloc
originally uses extra field of struct page, but, after this patch, it will
use field of struct page_ext.  Because memory for page_ext is allocated
later than initialization of page allocator in CONFIG_SPARSEMEM, we should
disable debug-pagealloc feature temporarily until initialization of
page_ext.  This patch implements this.

Signed-off-by: Joonsoo Kim 
Cc: Mel Gorman 
Cc: Johannes Weiner 
Cc: Minchan Kim 
Cc: Dave Hansen 
Cc: Michal Nazarewicz 
Cc: Jungsoo Son 
Cc: Ingo Molnar 
Cc: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2014-12-12T01:30:55+00:00

Pull s390 updates from Martin Schwidefsky:
 "The most notable change for this pull request is the ftrace rework
  from Heiko.  It brings a small performance improvement and the ground
  work to support a new gcc option to replace the mcount blocks with a
  single nop.

  Two new s390 specific system calls are added to emulate user space
  mmio for PCI, an artifact of the how PCI memory is accessed.

  Two patches for the memory management with changes to common code.
  For KVM mm_forbids_zeropage is added which disables the empty zero
  page for an mm that is used by a KVM process.  And an optimization,
  pmdp_get_and_clear_full is added analog to ptep_get_and_clear_full.

  Some micro optimization for the cmpxchg and the spinlock code.

  And as usual bug fixes and cleanups"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (46 commits)
  s390/cputime: fix 31-bit compile
  s390/scm_block: make the number of reqs per HW req configurable
  s390/scm_block: handle multiple requests in one HW request
  s390/scm_block: allocate aidaw pages only when necessary
  s390/scm_block: use mempool to manage aidaw requests
  s390/eadm: change timeout value
  s390/mm: fix memory leak of ptlock in pmd_free_tlb
  s390: use local symbol names in entry[64].S
  s390/ptrace: always include vector registers in core files
  s390/simd: clear vector register pointer on fork/clone
  s390: translate cputime magic constants to macros
  s390/idle: convert open coded idle time seqcount
  s390/idle: add missing irq off lockdep annotation
  s390/debug: avoid function call for debug_sprintf_*
  s390/kprobes: fix instruction copy for out of line execution
  s390: remove diag 44 calls from cpu_relax()
  s390/dasd: retry partition detection
  s390/dasd: fix list corruption for sleep_on requests
  s390/dasd: fix infinite term I/O loop
  s390/dasd: remove unused code
  ...

x86, mpx: Introduce VM_MPX to indicate that a VMA is MPX specific

2014-11-17T23:58:53+00:00

MPX-enabled applications using large swaths of memory can
potentially have large numbers of bounds tables in process
address space to save bounds information. These tables can take
up huge swaths of memory (as much as 80% of the memory on the
system) even if we clean them up aggressively. In the worst-case
scenario, the tables can be 4x the size of the data structure
being tracked. IOW, a 1-page structure can require 4 bounds-table
pages.

Being this huge, our expectation is that folks using MPX are
going to be keen on figuring out how much memory is being
dedicated to it. So we need a way to track memory use for MPX.

If we want to specifically track MPX VMAs we need to be able to
distinguish them from normal VMAs, and keep them from getting
merged with normal VMAs. A new VM_ flag set only on MPX VMAs does
both of those things. With this flag, MPX bounds-table VMAs can
be distinguished from other VMAs, and userspace can also walk
/proc/$pid/smaps to get memory usage for MPX.

In addition to this flag, we also introduce a special ->vm_ops
specific to MPX VMAs (see the patch "add MPX specific mmap
interface"), but currently different ->vm_ops do not by
themselves prevent VMA merging, so we still need this flag.

We understand that VM_ flags are scarce and are open to other
options.

Signed-off-by: Qiaowei Ren 
Signed-off-by: Dave Hansen 
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen 
Link: http://lkml.kernel.org/r/20141114151825.565625B3@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner

mm: page-writeback: inline account_page_dirtied() into single caller

2014-10-29T23:33:14+00:00

A follow-up patch would have changed the call signature.  To save the
trouble, just fold it instead.

Signed-off-by: Johannes Weiner 
Acked-by: Michal Hocko 
Cc: Vladimir Davydov 
Cc: 	[3.17.x]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: introduce mm_forbids_zeropage function

2014-10-27T12:27:24+00:00

Add a new function stub to allow architectures to disable for
an mm_structthe backing of non-present, anonymous pages with
read-only empty zero pages.

Signed-off-by: Dominik Dingel 
Reviewed-by: Paolo Bonzini 
Signed-off-by: Martin Schwidefsky

Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2014-10-20T16:50:11+00:00

Pull ext4 updates from Ted Ts'o:
 "A large number of cleanups and bug fixes, with some (minor) journal
  optimizations"

[ This got sent to me before -rc1, but was stuck in my spam folder.   - Linus ]

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (67 commits)
  ext4: check s_chksum_driver when looking for bg csum presence
  ext4: move error report out of atomic context in ext4_init_block_bitmap()
  ext4: Replace open coded mdata csum feature to helper function
  ext4: delete useless comments about ext4_move_extents
  ext4: fix reservation overflow in ext4_da_write_begin
  ext4: add ext4_iget_normal() which is to be used for dir tree lookups
  ext4: don't orphan or truncate the boot loader inode
  ext4: grab missed write_count for EXT4_IOC_SWAP_BOOT
  ext4: optimize block allocation on grow indepth
  ext4: get rid of code duplication
  ext4: fix over-defensive complaint after journal abort
  ext4: fix return value of ext4_do_update_inode
  ext4: fix mmap data corruption when blocksize < pagesize
  vfs: fix data corruption when blocksize < pagesize for mmaped data
  ext4: fold ext4_nojournal_sops into ext4_sops
  ext4: support freezing ext2 (nojournal) file systems
  ext4: fold ext4_sync_fs_nojournal() into ext4_sync_fs()
  ext4: don't check quota format when there are no quota files
  jbd2: simplify calling convention around __jbd2_journal_clean_checkpoint_list
  jbd2: avoid pointless scanning of checkpoint lists
  ...

mm: softdirty: enable write notifications on VMAs after VM_SOFTDIRTY cleared

2014-10-14T00:18:28+00:00

For VMAs that don't want write notifications, PTEs created for read faults
have their write bit set.  If the read fault happens after VM_SOFTDIRTY is
cleared, then the PTE's softdirty bit will remain clear after subsequent
writes.

Here's a simple code snippet to demonstrate the bug:

  char* m = mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE,
                 MAP_ANONYMOUS | MAP_SHARED, -1, 0);
  system("echo 4 > /proc/$PPID/clear_refs"); /* clear VM_SOFTDIRTY */
  assert(*m == '\0');     /* new PTE allows write access */
  assert(!soft_dirty(x));
  *m = 'x';               /* should dirty the page */
  assert(soft_dirty(x));  /* fails */

With this patch, write notifications are enabled when VM_SOFTDIRTY is
cleared.  Furthermore, to avoid unnecessary faults, write notifications
are disabled when VM_SOFTDIRTY is set.

As a side effect of enabling and disabling write notifications with
care, this patch fixes a bug in mprotect where vm_page_prot bits set by
drivers were zapped on mprotect.  An analogous bug was fixed in mmap by
commit c9d0bf241451 ("mm: uncached vma support with writenotify").

Signed-off-by: Peter Feiner 
Reported-by: Peter Feiner 
Suggested-by: Kirill A. Shutemov 
Cc: Cyrill Gorcunov 
Cc: Pavel Emelyanov 
Cc: Jamie Liu 
Cc: Hugh Dickins 
Cc: Naoya Horiguchi 
Cc: Bjorn Helgaas 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds