We don't track the reloc roots in any sort of normal way, so the only way the
root/commit_root nodes get free'd is if the relocation finishes successfully and
the reloc root is deleted.  Fix this by free'ing them in free_reloc_roots.
Thanks,
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Remove unneeded variables and assignments.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We need to check items in a node to make sure that we're reading
a valid one, otherwise we could get various crashes while processing
delayed_refs.
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Somehow we missed btrfs_print_tree when last time we
updated error handling for read_extent_block().

This keeps us from getting a NULL pointer panic when
btrfs_print_tree's read_extent_block() fails.
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Since we could get errors from the concurrent aborted transaction,
the check of this BUG_ON in start_transaction is not true any more.

Say, while flushing free space cache inode's dirty pages,
btrfs_finish_ordered_io
 -> btrfs_join_transaction_nolock
      (the transaction has been aborted.)
      -> BUG_ON(type == TRANS_JOIN_NOLOCK);
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

During updating btree, we could push items between sibling
nodes/leaves, for leaves data sections starts reversely from
the end of the block while for nodes we only have key pairs
which are stored one by one from the start of the block.

So we could do try to push key pairs from one node to the next
node right in the tree, and after that, we update the node's
nritems to reflect the correct end while leaving the stale
content in the node.  One may intentionally corrupt the fs
image and access the stale content by bumping the nritems and
causes various crashes.

This takes the in-memory @nritems as the correct one and
gets to memset the unused part of a btree node.
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When relocating tree blocks, we firstly get block information from
back references in the extent tree, we then search fs tree to try to
find all parents of a block.

However, if fs tree is corrupted, eg. if there're some missing
items, we could come across these WARN_ONs and BUG_ONs.

This makes us print some error messages and return gracefully
from balance.
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

No reason to bug on in here, fs corruption could easily cause these things to
happen.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Nobody uses this, it makes no sense to do partial reads of extent buffers.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We have a lot of random ints in btrfs_fs_info that can be put into flags.  This
is mostly equivalent with the exception of how we deal with quota going on or
off, now instead we set a flag when we are turning it on or off and deal with
that appropriately, rather than just having a pending state that the current
quota_enabled gets set to.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

btrfs: extend btrfs_set_extent_delalloc and its friends to support in-band dedupe and subpage size patchset

Extend btrfs_set_extent_delalloc() and extent_clear_unlock_delalloc()
parameters for both in-band dedupe and subpage sector size patchset.

This should reduce conflict of both patchset and the effort to rebase
them.

Cc: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Cc: David Sterba <dsterba@suse.cz>
Signed-off-by: NQu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We can re-use the dynamic debugging descriptor to make use of the dynamic
debugging mechanism but still use our own printk interface.

Defining the DEBUG macro works as it did before.  When it's defined,
all of the messages default to print.  We can also enable all debug
messages at boot or module-load time using the 'dyndbg' and
'btrfs.dyndbg' options.
Signed-off-by: NJeff Mahoney <jeffm@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Variable 'gen' in reada_for_search() is not used since commit 58dc4ce4
("btrfs: remove unused parameter from readahead_tree_block").  This patch
simply removes this variable.
Signed-off-by: NLuis Henriques <luis.henriques@canonical.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Variable 'blocksize' in reada_walk_down() is not used since commit
d3e46fea ("btrfs: sink blocksize parameter to readahead_tree_block").
This patch simply removes this variable.
Signed-off-by: NLuis Henriques <luis.henriques@canonical.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Currently, btrfs_relocate_chunk() is removing relocated BG by itself. But
the work can be done by btrfs_delete_unused_bgs() (and it's better since it
trim the BG). Let's dedupe the code.

While btrfs_delete_unused_bgs() is already hitting the relocated BG, it
skip the BG since the BG has "ro" flag set (to keep balancing BG intact).
On the other hand, btrfs cannot drop "ro" flag here to prevent additional
writes. So this patch make use of "removed" flag.
btrfs_delete_unused_bgs() now detect the flag to distinguish whether a
read-only BG is relocating or not.
Signed-off-by: NNaohiro Aota <naohiro.aota@hgst.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Currently we allow inconsistence about mixed flag
 (BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA).

We'd get ENOSPC if block group has mixed flag and btrfs doesn't.
If that happens, we have one space_info with mixed flag and another
space_info only with BTRFS_BLOCK_GROUP_METADATA, and
global_block_rsv.space_info points to the latter one, but all bytes
from block_group contributes to the mixed space_info, thus all the
allocation will fail with ENOSPC.

This adds a check for the above case.
Reported-by: NVegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
[ updated message ]
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

So we can read a btree block via readahead or intentional read,
and we can end up with a memory leak when something happens as
follows,
1) readahead starts to read block A but does not wait for read
   completion,
2) btree_readpage_end_io_hook finds that block A is corrupted,
   and it needs to clear all block A's pages' uptodate bit.
3) meanwhile an intentional read kicks in and checks block A's
   pages' uptodate to decide which page needs to be read.
4) when some pages have the uptodate bit during 3)'s check so
   3) doesn't count them for eb->io_pages, but they are later
   cleared by 2) so we has to readpage on the page, we get
   the wrong eb->io_pages which results in a memory leak of
   this block.

This fixes the problem by firstly getting all pages's locking and
then checking pages' uptodate bit.

   t1(readahead)                              t2(readahead endio)                                       t3(the following read)
read_extent_buffer_pages                    end_bio_extent_readpage
  for pg in eb:                                for page 0,1,2 in eb:
      if pg is uptodate:                           btree_readpage_end_io_hook(pg)
          num_reads++                              if uptodate:
  eb->io_pages = num_reads                             SetPageUptodate(pg)              _______________
  for pg in eb:                                for page 3 in eb:                                     read_extent_buffer_pages
       if pg is NOT uptodate:                      btree_readpage_end_io_hook(pg)                       for pg in eb:
           __extent_read_full_page(pg)                 sanity check reports something wrong                 if pg is uptodate:
                                                       clear_extent_buffer_uptodate(eb)                         num_reads++
                                                           for pg in eb:                                eb->io_pages = num_reads
                                                               ClearPageUptodate(page)  _______________
                                                                                                        for pg in eb:
                                                                                                            if pg is NOT uptodate:
                                                                                                                __extent_read_full_page(pg)

So t3's eb->io_pages is not consistent with the number of pages it's reading,
and during endio(), atomic_dec_and_test(&eb->io_pages) will get a negative
number so that we're not able to free the eb.
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This BUG() has been triggered by a fuzz testing image, which contains
an invalid chunk type, ie. a single stripe chunk has the raid6 type.

Btrfs can handle this gracefully by returning -EIO, so besides using
btrfs_warn to give us more debugging information rather than a single
BUG(), we can return error properly.
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Only in the case of different root_id or different object_id, check_shared
identified extent as the shared. However, If a extent was referred by
different offset of same file, it should also be identified as shared.
In addition, check_shared's loop scale is at least n^3, so if a extent
has too many references, even causes soft hang up.

First, add all delayed_ref to the ref_tree and calculate the unqiue_refs,
if the unique_refs is greater than one, return BACKREF_FOUND_SHARED.
Then individually add the on-disk reference(inline/keyed) to the ref_tree
and calculate the unique_refs of the ref_tree to check if the unique_refs
is greater than one.Because once there are two references to return
SHARED, so the time complexity is close to the constant.
Reported-by: NTsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: NLu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Reviewed-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

btrfs provides a helpful demonstration of how to export
a global variable via debugfs; however, it is unique among
other debugfs files in that it is world-writable, which causes
some concern to people who are not familiar with its purpose.

Fix it so that it is only user-writable.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

While processing delayed refs, we may update block group's statistics
and attach it to cur_trans->dirty_bgs, and later writing dirty block
groups will process the list, which happens during
btrfs_commit_transaction().

For whatever reason, the transaction is aborted and dirty_bgs
is not processed in cleanup_transaction(), we end up with memory leak
of these dirty block group cache.

Since btrfs_start_dirty_block_groups() doesn't make it go to the commit
critical section, this also adds the cleanup work inside it.
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Pull tracefs fixes from Steven Rostedt:
 "Al Viro has been looking at the tracefs code, and has pointed out some
  issues.  This contains one fix by me and one by Al.  I'm sure that
  he'll come up with more but for now I tested these patches and they
  don't appear to have any negative impact on tracing"

* tag 'trace-v4.8-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  fix memory leaks in tracing_buffers_splice_read()
  tracing: Move mutex to protect against resetting of seq data

When building XFS with -Werror, it now fails with:

  include/linux/pagemap.h: In function 'fault_in_multipages_readable':
  include/linux/pagemap.h:602:16: error: variable 'c' set but not used [-Werror=unused-but-set-variable]
    volatile char c;
                  ^

This is a regression caused by commit e23d4159 ("fix
fault_in_multipages_...() on architectures with no-op access_ok()").
Fix it by re-adding the "(void)c" trick taht was previously used to make
the compiler think the variable is used.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The NUMA balancing logic uses an arch-specific PROT_NONE page table flag
defined by pte_protnone() or pmd_protnone() to mark PTEs or huge page
PMDs respectively as requiring balancing upon a subsequent page fault.
User-defined PROT_NONE memory regions which also have this flag set will
not normally invoke the NUMA balancing code as do_page_fault() will send
a segfault to the process before handle_mm_fault() is even called.

However if access_remote_vm() is invoked to access a PROT_NONE region of
memory, handle_mm_fault() is called via faultin_page() and
__get_user_pages() without any access checks being performed, meaning
the NUMA balancing logic is incorrectly invoked on a non-NUMA memory
region.

A simple means of triggering this problem is to access PROT_NONE mmap'd
memory using /proc/self/mem which reliably results in the NUMA handling
functions being invoked when CONFIG_NUMA_BALANCING is set.

This issue was reported in bugzilla (issue 99101) which includes some
simple repro code.

There are BUG_ON() checks in do_numa_page() and do_huge_pmd_numa_page()
added at commit c0e7cad9 to avoid accidentally provoking strange
behaviour by attempting to apply NUMA balancing to pages that are in
fact PROT_NONE.  The BUG_ON()'s are consistently triggered by the repro.

This patch moves the PROT_NONE check into mm/memory.c rather than
invoking BUG_ON() as faulting in these pages via faultin_page() is a
valid reason for reaching the NUMA check with the PROT_NONE page table
flag set and is therefore not always a bug.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=99101Reported-by: NTrevor Saunders <tbsaunde@tbsaunde.org>
Signed-off-by: NLorenzo Stoakes <lstoakes@gmail.com>
Acked-by: NRik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Pull MIPS fixes from Ralf Baechle:
 "A round of 4.8 fixes:

  MIPS generic code:
   - Add a missing ".set pop" in an early commit
   - Fix memory regions reaching top of physical
   - MAAR: Fix address alignment
   - vDSO: Fix Malta EVA mapping to vDSO page structs
   - uprobes: fix incorrect uprobe brk handling
   - uprobes: select HAVE_REGS_AND_STACK_ACCESS_API
   - Avoid a BUG warning during PR_SET_FP_MODE prctl
   - SMP: Fix possibility of deadlock when bringing CPUs online
   - R6: Remove compact branch policy Kconfig entries
   - Fix size calc when avoiding IPIs for small icache flushes
   - Fix pre-r6 emulation FPU initialisation
   - Fix delay slot emulation count in debugfs

  ATH79:
   - Fix test for error return of clk_register_fixed_factor.

  Octeon:
   - Fix kernel header to work for VDSO build.
   - Fix initialization of platform device probing.

  paravirt:
   - Fix undefined reference to smp_bootstrap"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
  MIPS: Fix delay slot emulation count in debugfs
  MIPS: SMP: Fix possibility of deadlock when bringing CPUs online
  MIPS: Fix pre-r6 emulation FPU initialisation
  MIPS: vDSO: Fix Malta EVA mapping to vDSO page structs
  MIPS: Select HAVE_REGS_AND_STACK_ACCESS_API
  MIPS: Octeon: Fix platform bus probing
  MIPS: Octeon: mangle-port: fix build failure with VDSO code
  MIPS: Avoid a BUG warning during prctl(PR_SET_FP_MODE, ...)
  MIPS: c-r4k: Fix size calc when avoiding IPIs for small icache flushes
  MIPS: Add a missing ".set pop" in an early commit
  MIPS: paravirt: Fix undefined reference to smp_bootstrap
  MIPS: Remove compact branch policy Kconfig entries
  MIPS: MAAR: Fix address alignment
  MIPS: Fix memory regions reaching top of physical
  MIPS: uprobes: fix incorrect uprobe brk handling
  MIPS: ath79: Fix test for error return of clk_register_fixed_factor().

Pull one more powerpc fix from Michael Ellerman:
 "powernv/pci: Fix m64 checks for SR-IOV and window alignment from
  Russell Currey"

* tag 'powerpc-4.8-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/powernv/pci: Fix m64 checks for SR-IOV and window alignment

The fixes to the radix tree test suite show that the multi-order case is
broken.  The basic reason is that the radix tree code uses tagged
pointers with the "internal" bit in the low bits, and calculating the
pointer indices was supposed to mask off those bits.  But gcc will
notice that we then use the index to re-create the pointer, and will
avoid doing the arithmetic and use the tagged pointer directly.

This cleans the code up, using the existing is_sibling_entry() helper to
validate the sibling pointer range (instead of open-coding it), and
using entry_to_node() to mask off the low tag bit from the pointer.  And
once you do that, you might as well just use the now cleaned-up pointer
directly.

[ Side note: the multi-order code isn't actually ever used in the kernel
  right now, and the only reason I didn't just delete all that code is
  that Kirill Shutemov piped up and said:

    "Well, my ext4-with-huge-pages patchset[1] uses multi-order entries.
     It also converts shmem-with-huge-pages and hugetlb to them.

     I'm okay with converting it to other mechanism, but I need
     something.  (I looked into Konstantin's RFC patchset[2].  It looks
     okay, but I don't feel myself qualified to review it as I don't
     know much about radix-tree internals.)"

  [1] http://lkml.kernel.org/r/20160915115523.29737-1-kirill.shutemov@linux.intel.com
  [2] http://lkml.kernel.org/r/147230727479.9957.1087787722571077339.stgit@zurg ]
Reported-by: NMatthew Wilcox <mawilcox@microsoft.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Cedric Blancher <cedric.blancher@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When we replace a multiorder entry, check that all indices reflect the
new value.

Also, compile the test suite with -O2, which shows other problems with
the code due to some dodgy pointer operations in the radix tree code.
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Cc: stable@vger.kernel.org
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The iter->seq can be reset outside the protection of the mutex. So can
reading of user data. Move the mutex up to the beginning of the function.

Fixes: d7350c3f ("tracing/core: make the read callbacks reentrants")
Cc: stable@vger.kernel.org # 2.6.30+
Reported-by: NAl Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Commit 432c6bac ("MIPS: Use per-mm page to execute branch delay slot
instructions") accidentally removed use of the MIPS_FPU_EMU_INC_STATS
macro from do_dsemulret, leading to the ds_emul file in debugfs always
returning zero even though we perform delay slot emulations.

Fix this by re-adding the use of the MIPS_FPU_EMU_INC_STATS macro.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Fixes: 432c6bac ("MIPS: Use per-mm page to execute branch delay slot instructions")
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14301/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

This patch fixes the possibility of a deadlock when bringing up
secondary CPUs.
The deadlock occurs because the set_cpu_online() is called before
synchronise_count_slave(). This can cause a deadlock if the boot CPU,
having scheduled another thread, attempts to send an IPI to the
secondary CPU, which it sees has been marked online. The secondary is
blocked in synchronise_count_slave() waiting for the boot CPU to enter
synchronise_count_master(), but the boot cpu is blocked in
smp_call_function_many() waiting for the secondary to respond to it's
IPI request.

Fix this by marking the CPU online in cpu_callin_map and synchronising
counters before declaring the CPU online and calculating the maps for
IPIs.
Signed-off-by: NMatt Redfearn <matt.redfearn@imgtec.com>
Reported-by: NJustin Chen <justinpopo6@gmail.com>
Tested-by: NJustin Chen <justinpopo6@gmail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: stable@vger.kernel.org # v4.1+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14302/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Pull perf fixes from Thomas Gleixner:
 "Three fixlets for perf:

   - add a missing NULL pointer check in the intel BTS driver

   - make BTS an exclusive PMU because BTS can only handle one event at
     a time

   - ensure that exclusive events are limited to one PMU so that several
     exclusive events can be scheduled on different PMU instances"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/core: Limit matching exclusive events to one PMU
  perf/x86/intel/bts: Make it an exclusive PMU
  perf/x86/intel/bts: Make sure debug store is valid

Pull locking fixes from Thomas Gleixner:
 "Two smallish fixes:

   - use the proper asm constraint in the Super-H atomic_fetch_ops

   - a trivial typo fix in the Kconfig help text"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/hung_task: Fix typo in CONFIG_DETECT_HUNG_TASK help text
  locking/atomic, arch/sh: Fix ATOMIC_FETCH_OP()

Pull EFI fixes from Thomas Gleixner:
 "Two fixes for EFI/PAT:

   - a 32bit overflow bug in the PAT code which was unearthed by the
     large EFI mappings

   - prevent a boot hang on large systems when EFI mixed mode is enabled
     but not used"

* 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/efi: Only map RAM into EFI page tables if in mixed-mode
  x86/mm/pat: Prevent hang during boot when mapping pages

Pull irq fixes from Thomas Gleixner:
 "Three fixes for irq core and irq chip drivers:

   - Do not set the irq type if type is NONE.  Fixes a boot regression
     on various SoCs

   - Use the proper cpu for setting up the GIC target list.  Discovered
     by the cpumask debugging code.

   - A rather large fix for the MIPS-GIC so per cpu local interrupts
     work again.  This was discovered late because the code falls back
     to slower timers which use normal device interrupts"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/mips-gic: Fix local interrupts
  irqchip/gicv3: Silence noisy DEBUG_PER_CPU_MAPS warning
  genirq: Skip chained interrupt trigger setup if type is IRQ_TYPE_NONE

Merge VM fixes from High Dickins:
 "I get the impression that Andrew is away or busy at the moment, so I'm
  going to send you three independent uncontroversial little mm fixes
  directly - though none is strictly a 4.8 regression fix.

   - shmem: fix tmpfs to handle the huge= option properly from Toshi
     Kani is a one-liner to fix a major embarrassment in 4.8's hugepages
     on tmpfs feature: although Hillf pointed it out in June, somehow
     both Kirill and I repeatedly dropped the ball on this one.  You
     might wonder if the feature got tested at all with that bug in:
     yes, it did, but for wider testing coverage, Kirill and I had each
     relied too much on an override which bypasses that condition.

   - huge tmpfs: fix Committed_AS leak just a run-of-the-mill accounting
     fix in the same feature.

   - mm: delete unnecessary and unsafe init_tlb_ubc() is an unrelated
     fix to 4.3's TLB flush batching in reclaim: the bug would be rare,
     and none of us will be shamed if this one misses 4.8; but it got
     such a quick ack from Mel today that I'm inclined to offer it along
     with the first two"

* emailed patches from Hugh Dickins <hughd@google.com>:
  mm: delete unnecessary and unsafe init_tlb_ubc()
  huge tmpfs: fix Committed_AS leak
  shmem: fix tmpfs to handle the huge= option properly

init_tlb_ubc() looked unnecessary to me: tlb_ubc is statically
initialized with zeroes in the init_task, and copied from parent to
child while it is quiescent in arch_dup_task_struct(); so I went to
delete it.

But inserted temporary debug WARN_ONs in place of init_tlb_ubc() to
check that it was always empty at that point, and found them firing:
because memcg reclaim can recurse into global reclaim (when allocating
biosets for swapout in my case), and arrive back at the init_tlb_ubc()
in shrink_node_memcg().

Resetting tlb_ubc.flush_required at that point is wrong: if the upper
level needs a deferred TLB flush, but the lower level turns out not to,
we miss a TLB flush.  But fortunately, that's the only part of the
protocol that does not nest: with the initialization removed, cpumask
collects bits from upper and lower levels, and flushes TLB when needed.

Fixes: 72b252ae ("mm: send one IPI per CPU to TLB flush all entries after unmapping pages")
Signed-off-by: NHugh Dickins <hughd@google.com>
Acked-by: NMel Gorman <mgorman@techsingularity.net>
Cc: stable@vger.kernel.org # 4.3+
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>