linux.git/mm, branch v4.2-rc6

writeback: fix initial dirty limit

2015-08-07T01:39:42+00:00

The initial value of global_wb_domain.dirty_limit set by
writeback_set_ratelimit() is zeroed out by the memset in
wb_domain_init().

Signed-off-by: Rabin Vincent 
Acked-by: Tejun Heo 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/memory-failure: set PageHWPoison before migrate_pages()

2015-08-07T01:39:42+00:00

Now page freeing code doesn't consider PageHWPoison as a bad page, so by
setting it before completing the page containment, we can prevent the
error page from being reused just after successful page migration.

I added TTU_IGNORE_HWPOISON for try_to_unmap() to make sure that the
page table entry is transformed into migration entry, not to hwpoison
entry.

Signed-off-by: Naoya Horiguchi 
Cc: Andi Kleen 
Cc: Dean Nelson 
Cc: Tony Luck 
Cc: "Kirill A. Shutemov" 
Cc: Hugh Dickins 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: check __PG_HWPOISON separately from PAGE_FLAGS_CHECK_AT_*

2015-08-07T01:39:42+00:00

The race condition addressed in commit add05cecef80 ("mm: soft-offline:
don't free target page in successful page migration") was not closed
completely, because that can happen not only for soft-offline, but also
for hard-offline.  Consider that a slab page is about to be freed into
buddy pool, and then an uncorrected memory error hits the page just
after entering __free_one_page(), then VM_BUG_ON_PAGE(page->flags &
PAGE_FLAGS_CHECK_AT_PREP) is triggered, despite the fact that it's not
necessary because the data on the affected page is not consumed.

To solve it, this patch drops __PG_HWPOISON from page flag checks at
allocation/free time.  I think it's justified because __PG_HWPOISON
flags is defined to prevent the page from being reused, and setting it
outside the page's alloc-free cycle is a designed behavior (not a bug.)

For recent months, I was annoyed about BUG_ON when soft-offlined page
remains on lru cache list for a while, which is avoided by calling
put_page() instead of putback_lru_page() in page migration's success
path.  This means that this patch reverts a major change from commit
add05cecef80 about the new refcounting rule of soft-offlined pages, so
"reuse window" revives.  This will be closed by a subsequent patch.

Signed-off-by: Naoya Horiguchi 
Cc: Andi Kleen 
Cc: Dean Nelson 
Cc: Tony Luck 
Cc: "Kirill A. Shutemov" 
Cc: Hugh Dickins 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/memory-failure: give up error handling for non-tail-refcounted thp

2015-08-07T01:39:41+00:00

"non anonymous thp" case is still racy with freeing thp, which causes
panic due to put_page() for refcount-0 page.  It seems that closing up
this race might be hard (and/or not worth doing,) so let's give up the
error handling for this case.

Signed-off-by: Naoya Horiguchi 
Cc: Andi Kleen 
Cc: Dean Nelson 
Cc: Tony Luck 
Cc: "Kirill A. Shutemov" 
Cc: Hugh Dickins 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/memory-failure: fix race in counting num_poisoned_pages

2015-08-07T01:39:41+00:00

When memory_failure() is called on a page which are just freed after
page migration from soft offlining, the counter num_poisoned_pages is
raised twi= ce.  So let's fix it with using TestSetPageHWPoison.

Signed-off-by: Naoya Horiguchi 
Cc: Andi Kleen 
Cc: Dean Nelson 
Cc: Tony Luck 
Cc: "Kirill A. Shutemov" 
Cc: Hugh Dickins 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/memory-failure: unlock_page before put_page

2015-08-07T01:39:41+00:00

Recently I addressed a few of hwpoison race problems and the patches are
merged on v4.2-rc1.  It made progress, but unfortunately some problems
still remain due to less coverage of my testing.  So I'm trying to fix
or avoid them in this series.

One point I'm expecting to discuss is that patch 4/5 changes the page
flag set to be checked on free time.  In current behavior, __PG_HWPOISON
is not supposed to be set when the page is freed.  I think that there is
no strong reason for this behavior, and it causes a problem hard to fix
only in error handler side (because __PG_HWPOISON could be set at
arbitrary timing.) So I suggest to change it.

With this patchset, hwpoison stress testing in official mce-test
testsuite (which previously failed) passes.

This patch (of 5):

In "just unpoisoned" path, we do put_page and then unlock_page, which is
a wrong order and causes "freeing locked page" bug.  So let's fix it.

Signed-off-by: Naoya Horiguchi 
Cc: Andi Kleen 
Cc: Dean Nelson 
Cc: Tony Luck 
Cc: "Kirill A. Shutemov" 
Cc: Hugh Dickins 
Acked-by: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc: use private shmem or hugetlbfs inodes for shm segments.

2015-08-07T01:39:41+00:00

The shm implementation internally uses shmem or hugetlbfs inodes for shm
segments.  As these inodes are never directly exposed to userspace and
only accessed through the shm operations which are already hooked by
security modules, mark the inodes with the S_PRIVATE flag so that inode
security initialization and permission checking is skipped.

This was motivated by the following lockdep warning:

  ======================================================
   [ INFO: possible circular locking dependency detected ]
   4.2.0-0.rc3.git0.1.fc24.x86_64+debug #1 Tainted: G        W
  -------------------------------------------------------
   httpd/1597 is trying to acquire lock:
   (&ids->rwsem){+++++.}, at: shm_close+0x34/0x130
   but task is already holding lock:
   (&mm->mmap_sem){++++++}, at: SyS_shmdt+0x4b/0x180
   which lock already depends on the new lock.
   the existing dependency chain (in reverse order) is:
   -> #3 (&mm->mmap_sem){++++++}:
        lock_acquire+0xc7/0x270
        __might_fault+0x7a/0xa0
        filldir+0x9e/0x130
        xfs_dir2_block_getdents.isra.12+0x198/0x1c0 [xfs]
        xfs_readdir+0x1b4/0x330 [xfs]
        xfs_file_readdir+0x2b/0x30 [xfs]
        iterate_dir+0x97/0x130
        SyS_getdents+0x91/0x120
        entry_SYSCALL_64_fastpath+0x12/0x76
   -> #2 (&xfs_dir_ilock_class){++++.+}:
        lock_acquire+0xc7/0x270
        down_read_nested+0x57/0xa0
        xfs_ilock+0x167/0x350 [xfs]
        xfs_ilock_attr_map_shared+0x38/0x50 [xfs]
        xfs_attr_get+0xbd/0x190 [xfs]
        xfs_xattr_get+0x3d/0x70 [xfs]
        generic_getxattr+0x4f/0x70
        inode_doinit_with_dentry+0x162/0x670
        sb_finish_set_opts+0xd9/0x230
        selinux_set_mnt_opts+0x35c/0x660
        superblock_doinit+0x77/0xf0
        delayed_superblock_init+0x10/0x20
        iterate_supers+0xb3/0x110
        selinux_complete_init+0x2f/0x40
        security_load_policy+0x103/0x600
        sel_write_load+0xc1/0x750
        __vfs_write+0x37/0x100
        vfs_write+0xa9/0x1a0
        SyS_write+0x58/0xd0
        entry_SYSCALL_64_fastpath+0x12/0x76
  ...

Signed-off-by: Stephen Smalley 
Reported-by: Morten Stevens 
Acked-by: Hugh Dickins 
Acked-by: Paul Moore 
Cc: Manfred Spraul 
Cc: Davidlohr Bueso 
Cc: Prarit Bhargava 
Cc: Eric Paris 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: initialize hotplugged pages as reserved

2015-08-07T01:39:41+00:00

Commit 92923ca3aace ("mm: meminit: only set page reserved in the
memblock region") broke memory hotplug which expects the memmap for
newly added sections to be reserved until onlined by
online_pages_range().  This patch marks hotplugged pages as reserved
when adding new zones.

Signed-off-by: Mel Gorman 
Reported-by: David Vrabel 
Tested-by: David Vrabel 
Cc: Nathan Zimmer 
Cc: Robin Holt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/slub: allow merging when SLAB_DEBUG_FREE is set

2015-08-07T01:39:40+00:00

This patch fixes creation of new kmem-caches after enabling
sanity_checks for existing mergeable kmem-caches in runtime: before that
patch creation fails because unique name in sysfs already taken by
existing kmem-cache.

Unlike other debug options this doesn't change object layout and could
be enabled and disabled at any time.

Signed-off-by: Konstantin Khlebnikov 
Acked-by: Christoph Lameter 
Cc: Pekka Enberg 
Acked-by: David Rientjes 
Cc: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs, file table: reinit files_stat.max_files after deferred memory initialisation

2015-08-07T01:39:40+00:00

Dave Hansen reported the following;

	My laptop has been behaving strangely with 4.2-rc2.  Once I log
	in to my X session, I start getting all kinds of strange errors
	from applications and see this in my dmesg:

        	VFS: file-max limit 8192 reached

The problem is that the file-max is calculated before memory is fully
initialised and miscalculates how much memory the kernel is using.  This
patch recalculates file-max after deferred memory initialisation.  Note
that using memory hotplug infrastructure would not have avoided this
problem as the value is not recalculated after memory hot-add.

4.1:             files_stat.max_files = 6582781
4.2-rc2:         files_stat.max_files = 8192
4.2-rc2 patched: files_stat.max_files = 6562467

Small differences with the patch applied and 4.1 but not enough to matter.

Signed-off-by: Mel Gorman 
Reported-by: Dave Hansen 
Cc: Nicolai Stange 
Cc: Dave Hansen 
Cc: Alex Ng 
Cc: Fengguang Wu 
Cc: Peter Zijlstra (Intel) 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds