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  1. 22 Aug, 2015 3 commits
    • Thomas Gleixner's avatar
      x86/apic: Fix fallout from x2apic cleanup · a57e456a
      Thomas Gleixner authored 
      In the recent x2apic cleanup I got two things really wrong:
1) The safety check in __disable_x2apic which allows the function to
   be called unconditionally is backwards. The check is there to
   prevent access to the apic MSR in case that the machine has no
   apic. Though right now it returns if the machine has an apic and
   therefor the disabling of x2apic is never invoked.

2) x2apic_disable() sets x2apic_mode to 0 after registering the local
   apic. That's wrong, because register_lapic_address() checks x2apic
   mode and therefor takes the wrong code path.

This results in boot failures on machines with x2apic preenabled by
BIOS and can also lead to an fatal MSR access on machines without
apic.

The solutions are simple:
1) Correct the sanity check for apic availability
2) Clear x2apic_mode _before_ calling register_lapic_address()

Fixes: 659006bf 'x86/x2apic: Split enable and setup function'
Reported-and-tested-by: default avatarJavier Monteagudo <javiermon@gmail.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1224764
Cc: stable@vger.kernel.org # 4.0+
Cc: Laura Abbott <labbott@redhat.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
      a57e456a
    • Ingo Molnar's avatar
      x86/fpu/math-emu: Fix crash in fork() · 827409b2
      Ingo Molnar authored 
      During later stages of math-emu bootup the following crash triggers:

	 math_emulate: 0060:c100d0a8
	 Kernel panic - not syncing: Math emulation needed in kernel
	 CPU: 0 PID: 1511 Comm: login Not tainted 4.2.0-rc7+ #1012
	 [...]
	 Call Trace:
	  [<c181d50d>] dump_stack+0x41/0x52
	  [<c181c918>] panic+0x77/0x189
	  [<c1003530>] ? math_error+0x140/0x140
	  [<c164c2d7>] math_emulate+0xba7/0xbd0
	  [<c100d0a8>] ? fpu__copy+0x138/0x1c0
	  [<c1109c3c>] ? __alloc_pages_nodemask+0x12c/0x870
	  [<c136ac20>] ? proc_clear_tty+0x40/0x70
	  [<c136ac6e>] ? session_clear_tty+0x1e/0x30
	  [<c1003530>] ? math_error+0x140/0x140
	  [<c1003575>] do_device_not_available+0x45/0x70
	  [<c100d0a8>] ? fpu__copy+0x138/0x1c0
	  [<c18258e6>] error_code+0x5a/0x60
	  [<c1003530>] ? math_error+0x140/0x140
	  [<c100d0a8>] ? fpu__copy+0x138/0x1c0
	  [<c100c205>] arch_dup_task_struct+0x25/0x30
	  [<c1048cea>] copy_process.part.51+0xea/0x1480
	  [<c115a8e5>] ? dput+0x175/0x200
	  [<c136af70>] ? no_tty+0x30/0x30
	  [<c1157242>] ? do_vfs_ioctl+0x322/0x540
	  [<c104a21a>] _do_fork+0xca/0x340
	  [<c1057b06>] ? SyS_rt_sigaction+0x66/0x90
	  [<c104a557>] SyS_clone+0x27/0x30
	  [<c1824a80>] sysenter_do_call+0x12/0x12

The reason is the incorrect assumption in fpu_copy(), that FNSAVE
can be executed from math-emu kernels as well.

Don't try to copy the registers, the soft state will be copied
by fork anyway, so the child task inherits the parent task's
soft math state.

With this fix applied math-emu kernels boot up fine on modern
hardware and the 'no387 nofxsr' boot options.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      827409b2
    • Ingo Molnar's avatar
      x86/fpu/math-emu: Fix math-emu boot crash · 5fc96038
      Ingo Molnar authored 
      On a math-emu bootup the following crash occurs:

	Initializing CPU#0
	------------[ cut here ]------------
	kernel BUG at arch/x86/kernel/traps.c:779!
	invalid opcode: 0000 [#1] SMP
	[...]
	EIP is at do_device_not_available+0xe/0x70
	[...]
	Call Trace:
	 [<c18238e6>] error_code+0x5a/0x60
	 [<c1002bd0>] ? math_error+0x140/0x140
	 [<c100bbd9>] ? fpu__init_cpu+0x59/0xa0
	 [<c1012322>] cpu_init+0x202/0x330
	 [<c104509f>] ? __native_set_fixmap+0x1f/0x30
	 [<c1b56ab0>] trap_init+0x305/0x346
	 [<c1b548af>] start_kernel+0x1a5/0x35d
	 [<c1b542b4>] i386_start_kernel+0x82/0x86

The reason is that in the following commit:

  b1276c48 ("x86/fpu: Initialize fpregs in fpu__init_cpu_generic()")

I failed to consider math-emu's limitation that it cannot execute the
FNINIT instruction in kernel mode.

The long term fix might be to allow math-emu to execute (certain) kernel
mode FPU instructions, but for now apply the safe (albeit somewhat ugly)
fix: initialize the emulation state explicitly without trapping out to
the FPU emulator.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      5fc96038
  3. 20 Aug, 2015 1 commit
  5. 19 Aug, 2015 1 commit
  7. 18 Aug, 2015 2 commits
  9. 17 Aug, 2015 1 commit
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 · a36304b9
      Linus Torvalds authored 
      Pull crypto fixes from Herbert Xu:
 "This fixes the following issues:

   - a regression caused by the conversion of IPsec ESP to the new AEAD
     interface: ESN with authencesn no longer works because it relied on
     the AD input SG list having a specific layout which is no longer
     the case.  In linux-next authencesn is fixed properly and no longer
     assumes anything about the SG list format.  While for this release
     a minimal fix is applied to authencesn so that it works with the
     new linear layout.

   - fix memory corruption caused by bogus index in the caam hash code.

   - fix powerpc nx SHA hashing which could cause module load failures
     if module signature verification is enabled"

* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: caam - fix memory corruption in ahash_final_ctx
  crypto: nx - respect sg limit bounds when building sg lists for SHA
  crypto: authencesn - Fix breakage with new ESP code
      a36304b9
  11. 16 Aug, 2015 8 commits
  13. 15 Aug, 2015 3 commits
    • Linus Torvalds's avatar
      Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi · 1efdb5f0
      Linus Torvalds authored 
      Pull SCSI fixes from James Bottomley:
 "This has two libfc fixes for bugs causing rare crashes, one iscsi fix
  for a potential hang on shutdown, and a fix for an I/O blocksize issue
  which caused a regression"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  sd: Fix maximum I/O size for BLOCK_PC requests
  libfc: Fix fc_fcp_cleanup_each_cmd()
  libfc: Fix fc_exch_recv_req() error path
  libiscsi: Fix host busy blocking during connection teardown
      1efdb5f0
    • Linus Torvalds's avatar
      Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm · 45e38cff
      Linus Torvalds authored 
      Pull KVM fixes from Paolo Bonzini:
 "Just two very small & simple patches"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86: Use adjustment in guest cycles when handling MSR_IA32_TSC_ADJUST
  KVM: x86: zero IDT limit on entry to SMM
      45e38cff
    • Linus Torvalds's avatar
      Merge branch 'akpm' (patches from Andrew) · 8394a1b7
      Linus Torvalds authored 
      Merge fixes from Andrew Morton:
 "11 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  Update maintainers for DRM STI driver
  mm: cma: mark cma_bitmap_maxno() inline in header
  zram: fix pool name truncation
  memory-hotplug: fix wrong edge when hot add a new node
  .mailmap: Andrey Ryabinin has moved
  ipc/sem.c: update/correct memory barriers
  mm/hwpoison: fix panic due to split huge zero page
  ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()
  ipc,sem: fix use after free on IPC_RMID after a task using same semaphore set exits
  mm/hwpoison: fix fail isolate hugetlbfs page w/ refcount held
  mm/hwpoison: fix page refcount of unknown non LRU page
      8394a1b7
  15. 14 Aug, 2015 16 commits
    • Linus Torvalds's avatar
      Merge tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux · fbd9163f
      Linus Torvalds authored 
      Pull clock fix from Stephen Boyd:
 "A one-liner for a regression found in the PXA clock driver"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: pxa: pxa3xx: fix CKEN register access
      fbd9163f
    • Benjamin Gaignard's avatar
      Update maintainers for DRM STI driver · 7f11c476
      Benjamin Gaignard authored 
      Add Vincent Abriou and myself as maintainers.
Signed-off-by: default avatarBenjamin Gaignard <benjamin.gaignard@linaro.org>
Cc: Vincent Abriou <vincent.abriou@st.com>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7f11c476
    • Gregory Fong's avatar
      mm: cma: mark cma_bitmap_maxno() inline in header · f21838e0
      Gregory Fong authored 
      cma_bitmap_maxno() was marked as static and not static inline, which can
cause warnings about this function not being used if this file is included
in a file that does not call that function, and violates the conventions
used elsewhere.  The two options are to move the function implementation
back to mm/cma.c or make it inline here, and it's simple enough for the
latter to make sense.
Signed-off-by: default avatarGregory Fong <gregory.0xf0@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f21838e0
    • Sergey Senozhatsky's avatar
      zram: fix pool name truncation · 4ce321f5
      Sergey Senozhatsky authored 
      zram_meta_alloc() constructs a pool name for zs_create_pool() call as

    snprintf(pool_name, sizeof(pool_name), "zram%d", device_id);

However, it defines pool name buffer to be only 8 bytes long (minus
trailing zero), which means that we can have only 1000 pool names: zram0
-- zram999.

With CONFIG_ZSMALLOC_STAT enabled an attempt to create a device zram1000
can fail if device zram100 already exists, because snprintf() will
truncate new pool name to zram100 and pass it debugfs_create_dir(),
causing:

  debugfs dir <zram100> creation failed
  zram: Error creating memory pool

... and so on.

Fix it by passing zram->disk->disk_name to zram_meta_alloc() instead of
divice_id.  We construct zram%d name earlier and keep it as a ->disk_name,
no need to snprintf() it again.
Signed-off-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      4ce321f5
    • Xishi Qiu's avatar
      memory-hotplug: fix wrong edge when hot add a new node · f9126ab9
      Xishi Qiu authored 
      When we add a new node, the edge of memory may be wrong.

e.g. system has 4 nodes, and node3 is movable, node3 mem:[24G-32G],

1. hotremove the node3,
2. then hotadd node3 with a part of memory, mem:[26G-30G],
3. call hotadd_new_pgdat()
        free_area_init_node()
                get_pfn_range_for_nid()
4. it will return wrong start_pfn and end_pfn, because we have not
update the memblock.

This patch also fixes a BUG_ON during hot-addition, please see
http://marc.info/?l=linux-kernel&m=142961156129456&w=2Signed-off-by: default avatarXishi Qiu <qiuxishi@huawei.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f9126ab9
    • Andrey Ryabinin's avatar
      .mailmap: Andrey Ryabinin has moved · 2baf9e89
      Andrey Ryabinin authored 
      Update my email address.
Signed-off-by: default avatarAndrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2baf9e89
    • Manfred Spraul's avatar
      ipc/sem.c: update/correct memory barriers · 3ed1f8a9
      Manfred Spraul authored 
      sem_lock() did not properly pair memory barriers:

!spin_is_locked() and spin_unlock_wait() are both only control barriers.
The code needs an acquire barrier, otherwise the cpu might perform read
operations before the lock test.

As no primitive exists inside <include/spinlock.h> and since it seems
noone wants another primitive, the code creates a local primitive within
ipc/sem.c.

With regards to -stable:

The change of sem_wait_array() is a bugfix, the change to sem_lock() is a
nop (just a preprocessor redefinition to improve the readability).  The
bugfix is necessary for all kernels that use sem_wait_array() (i.e.:
starting from 3.10).
Signed-off-by: default avatarManfred Spraul <manfred@colorfullife.com>
Reported-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Kirill Tkhai <ktkhai@parallels.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: <stable@vger.kernel.org>	[3.10+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3ed1f8a9
    • Wanpeng Li's avatar
      mm/hwpoison: fix panic due to split huge zero page · 7f6bf39b
      Wanpeng Li authored 
      Bug:

  ------------[ cut here ]------------
  kernel BUG at mm/huge_memory.c:1957!
  invalid opcode: 0000 [#1] SMP
  Modules linked in: snd_hda_codec_hdmi i915 rpcsec_gss_krb5 snd_hda_codec_realtek snd_hda_codec_generic nfsv4 dns_re
  CPU: 2 PID: 2576 Comm: test_huge Not tainted 4.2.0-rc5-mm1+ #27
  Hardware name: Dell Inc. OptiPlex 7020/0F5C5X, BIOS A03 01/08/2015
  task: ffff880204e3d600 ti: ffff8800db16c000 task.ti: ffff8800db16c000
  RIP: split_huge_page_to_list+0xdb/0x120
  Call Trace:
    memory_failure+0x32e/0x7c0
    madvise_hwpoison+0x8b/0x160
    SyS_madvise+0x40/0x240
    ? do_page_fault+0x37/0x90
    entry_SYSCALL_64_fastpath+0x12/0x71
  Code: ff f0 41 ff 4c 24 30 74 0d 31 c0 48 83 c4 08 5b 41 5c 41 5d c9 c3 4c 89 e7 e8 e2 58 fd ff 48 83 c4 08 31 c0
  RIP  split_huge_page_to_list+0xdb/0x120
   RSP <ffff8800db16fde8>
  ---[ end trace aee7ce0df8e44076 ]---

Testcase:

    #define _GNU_SOURCE
    #include <stdlib.h>
    #include <stdio.h>
    #include <sys/mman.h>
    #include <unistd.h>
    #include <fcntl.h>
    #include <sys/types.h>
    #include <errno.h>
    #include <string.h>

    #define MB 1024*1024

    int main(void)
    {
            char *mem;

            posix_memalign((void **)&mem, 2 * MB, 200 * MB);

            madvise(mem, 200 * MB, MADV_HWPOISON);

            free(mem);

            return 0;
    }

Huge zero page is allocated if page fault w/o FAULT_FLAG_WRITE flag.
The get_user_pages_fast() which called in madvise_hwpoison() will get
huge zero page if the page is not allocated before.  Huge zero page is a
tranparent huge page, however, it is not an anonymous page.
memory_failure will split the huge zero page and trigger
BUG_ON(is_huge_zero_page(page));

After commit 98ed2b00 ("mm/memory-failure: give up error handling
for non-tail-refcounted thp"), memory_failure will not catch non anon
thp from madvise_hwpoison path and this bug occur.

Fix it by catching non anon thp in memory_failure in order to not split
huge zero page in madvise_hwpoison path.

After this patch:

  Injecting memory failure for page 0x202800 at 0x7fd8ae800000
  MCE: 0x202800: non anonymous thp
  [...]

[akpm@linux-foundation.org: remove second split, per Wanpeng]
Signed-off-by: default avatarWanpeng Li <wanpeng.li@hotmail.com>
Acked-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7f6bf39b
    • Herton R. Krzesinski's avatar
      ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem() · a9795584
      Herton R. Krzesinski authored 
      After we acquire the sma->sem_perm lock in exit_sem(), we are protected
against a racing IPC_RMID operation.  Also at that point, we are the last
user of sem_undo_list.  Therefore it isn't required that we acquire or use
ulp->lock.
Signed-off-by: default avatarHerton R. Krzesinski <herton@redhat.com>
Acked-by: default avatarManfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Rafael Aquini <aquini@redhat.com>
CC: Aristeu Rozanski <aris@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a9795584
    • Herton R. Krzesinski's avatar
      ipc,sem: fix use after free on IPC_RMID after a task using same semaphore set exits · 602b8593
      Herton R. Krzesinski authored 
      The current semaphore code allows a potential use after free: in
exit_sem we may free the task's sem_undo_list while there is still
another task looping through the same semaphore set and cleaning the
sem_undo list at freeary function (the task called IPC_RMID for the same
semaphore set).

For example, with a test program [1] running which keeps forking a lot
of processes (which then do a semop call with SEM_UNDO flag), and with
the parent right after removing the semaphore set with IPC_RMID, and a
kernel built with CONFIG_SLAB, CONFIG_SLAB_DEBUG and
CONFIG_DEBUG_SPINLOCK, you can easily see something like the following
in the kernel log:

   Slab corruption (Not tainted): kmalloc-64 start=ffff88003b45c1c0, len=64
   000: 6b 6b 6b 6b 6b 6b 6b 6b 00 6b 6b 6b 6b 6b 6b 6b  kkkkkkkk.kkkkkkk
   010: ff ff ff ff 6b 6b 6b 6b ff ff ff ff ff ff ff ff  ....kkkk........
   Prev obj: start=ffff88003b45c180, len=64
   000: 00 00 00 00 ad 4e ad de ff ff ff ff 5a 5a 5a 5a  .....N......ZZZZ
   010: ff ff ff ff ff ff ff ff c0 fb 01 37 00 88 ff ff  ...........7....
   Next obj: start=ffff88003b45c200, len=64
   000: 00 00 00 00 ad 4e ad de ff ff ff ff 5a 5a 5a 5a  .....N......ZZZZ
   010: ff ff ff ff ff ff ff ff 68 29 a7 3c 00 88 ff ff  ........h).<....
   BUG: spinlock wrong CPU on CPU#2, test/18028
   general protection fault: 0000 [#1] SMP
   Modules linked in: 8021q mrp garp stp llc nf_conntrack_ipv4 nf_defrag_ipv4 ip6t_REJECT nf_reject_ipv6 nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables binfmt_misc ppdev input_leds joydev parport_pc parport floppy serio_raw virtio_balloon virtio_rng virtio_console virtio_net iosf_mbi crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcspkr qxl ttm drm_kms_helper drm snd_hda_codec_generic i2c_piix4 snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm snd_timer snd soundcore crc32c_intel virtio_pci virtio_ring virtio pata_acpi ata_generic [last unloaded: speedstep_lib]
   CPU: 2 PID: 18028 Comm: test Not tainted 4.2.0-rc5+ #1
   Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.1-20150318_183358- 04/01/2014
   RIP: spin_dump+0x53/0xc0
   Call Trace:
     spin_bug+0x30/0x40
     do_raw_spin_unlock+0x71/0xa0
     _raw_spin_unlock+0xe/0x10
     freeary+0x82/0x2a0
     ? _raw_spin_lock+0xe/0x10
     semctl_down.clone.0+0xce/0x160
     ? __do_page_fault+0x19a/0x430
     ? __audit_syscall_entry+0xa8/0x100
     SyS_semctl+0x236/0x2c0
     ? syscall_trace_leave+0xde/0x130
     entry_SYSCALL_64_fastpath+0x12/0x71
   Code: 8b 80 88 03 00 00 48 8d 88 60 05 00 00 48 c7 c7 a0 2c a4 81 31 c0 65 8b 15 eb 40 f3 7e e8 08 31 68 00 4d 85 e4 44 8b 4b 08 74 5e <45> 8b 84 24 88 03 00 00 49 8d 8c 24 60 05 00 00 8b 53 04 48 89
   RIP  [<ffffffff810d6053>] spin_dump+0x53/0xc0
    RSP <ffff88003750fd68>
   ---[ end trace 783ebb76612867a0 ]---
   NMI watchdog: BUG: soft lockup - CPU#3 stuck for 22s! [test:18053]
   Modules linked in: 8021q mrp garp stp llc nf_conntrack_ipv4 nf_defrag_ipv4 ip6t_REJECT nf_reject_ipv6 nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables binfmt_misc ppdev input_leds joydev parport_pc parport floppy serio_raw virtio_balloon virtio_rng virtio_console virtio_net iosf_mbi crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcspkr qxl ttm drm_kms_helper drm snd_hda_codec_generic i2c_piix4 snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm snd_timer snd soundcore crc32c_intel virtio_pci virtio_ring virtio pata_acpi ata_generic [last unloaded: speedstep_lib]
   CPU: 3 PID: 18053 Comm: test Tainted: G      D         4.2.0-rc5+ #1
   Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.1-20150318_183358- 04/01/2014
   RIP: native_read_tsc+0x0/0x20
   Call Trace:
     ? delay_tsc+0x40/0x70
     __delay+0xf/0x20
     do_raw_spin_lock+0x96/0x140
     _raw_spin_lock+0xe/0x10
     sem_lock_and_putref+0x11/0x70
     SYSC_semtimedop+0x7bf/0x960
     ? handle_mm_fault+0xbf6/0x1880
     ? dequeue_task_fair+0x79/0x4a0
     ? __do_page_fault+0x19a/0x430
     ? kfree_debugcheck+0x16/0x40
     ? __do_page_fault+0x19a/0x430
     ? __audit_syscall_entry+0xa8/0x100
     ? do_audit_syscall_entry+0x66/0x70
     ? syscall_trace_enter_phase1+0x139/0x160
     SyS_semtimedop+0xe/0x10
     SyS_semop+0x10/0x20
     entry_SYSCALL_64_fastpath+0x12/0x71
   Code: 47 10 83 e8 01 85 c0 89 47 10 75 08 65 48 89 3d 1f 74 ff 7e c9 c3 0f 1f 44 00 00 55 48 89 e5 e8 87 17 04 00 66 90 c9 c3 0f 1f 00 <55> 48 89 e5 0f 31 89 c1 48 89 d0 48 c1 e0 20 89 c9 48 09 c8 c9
   Kernel panic - not syncing: softlockup: hung tasks

I wasn't able to trigger any badness on a recent kernel without the
proper config debugs enabled, however I have softlockup reports on some
kernel versions, in the semaphore code, which are similar as above (the
scenario is seen on some servers running IBM DB2 which uses semaphore
syscalls).

The patch here fixes the race against freeary, by acquiring or waiting
on the sem_undo_list lock as necessary (exit_sem can race with freeary,
while freeary sets un->semid to -1 and removes the same sem_undo from
list_proc or when it removes the last sem_undo).

After the patch I'm unable to reproduce the problem using the test case
[1].

[1] Test case used below:

    #include <stdio.h>
    #include <sys/types.h>
    #include <sys/ipc.h>
    #include <sys/sem.h>
    #include <sys/wait.h>
    #include <stdlib.h>
    #include <time.h>
    #include <unistd.h>
    #include <errno.h>

    #define NSEM 1
    #define NSET 5

    int sid[NSET];

    void thread()
    {
            struct sembuf op;
            int s;
            uid_t pid = getuid();

            s = rand() % NSET;
            op.sem_num = pid % NSEM;
            op.sem_op = 1;
            op.sem_flg = SEM_UNDO;

            semop(sid[s], &op, 1);
            exit(EXIT_SUCCESS);
    }

    void create_set()
    {
            int i, j;
            pid_t p;
            union {
                    int val;
                    struct semid_ds *buf;
                    unsigned short int *array;
                    struct seminfo *__buf;
            } un;

            /* Create and initialize semaphore set */
            for (i = 0; i < NSET; i++) {
                    sid[i] = semget(IPC_PRIVATE , NSEM, 0644 | IPC_CREAT);
                    if (sid[i] < 0) {
                            perror("semget");
                            exit(EXIT_FAILURE);
                    }
            }
            un.val = 0;
            for (i = 0; i < NSET; i++) {
                    for (j = 0; j < NSEM; j++) {
                            if (semctl(sid[i], j, SETVAL, un) < 0)
                                    perror("semctl");
                    }
            }

            /* Launch threads that operate on semaphore set */
            for (i = 0; i < NSEM * NSET * NSET; i++) {
                    p = fork();
                    if (p < 0)
                            perror("fork");
                    if (p == 0)
                            thread();
            }

            /* Free semaphore set */
            for (i = 0; i < NSET; i++) {
                    if (semctl(sid[i], NSEM, IPC_RMID))
                            perror("IPC_RMID");
            }

            /* Wait for forked processes to exit */
            while (wait(NULL)) {
                    if (errno == ECHILD)
                            break;
            };
    }

    int main(int argc, char **argv)
    {
            pid_t p;

            srand(time(NULL));

            while (1) {
                    p = fork();
                    if (p < 0) {
                            perror("fork");
                            exit(EXIT_FAILURE);
                    }
                    if (p == 0) {
                            create_set();
                            goto end;
                    }

                    /* Wait for forked processes to exit */
                    while (wait(NULL)) {
                            if (errno == ECHILD)
                                    break;
                    };
            }
    end:
            return 0;
    }

[akpm@linux-foundation.org: use normal comment layout]
Signed-off-by: default avatarHerton R. Krzesinski <herton@redhat.com>
Acked-by: default avatarManfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Rafael Aquini <aquini@redhat.com>
CC: Aristeu Rozanski <aris@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      602b8593
    • Wanpeng Li's avatar
      mm/hwpoison: fix fail isolate hugetlbfs page w/ refcount held · 03613808
      Wanpeng Li authored 
      Hugetlbfs pages will get a refcount in get_any_page() or
madvise_hwpoison() if soft offlining through madvise.  The refcount which
is held by the soft offline path should be released if we fail to isolate
hugetlbfs pages.

Fix it by reducing the refcount for both isolation success and failure.
Signed-off-by: default avatarWanpeng Li <wanpeng.li@hotmail.com>
Acked-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>	[3.9+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      03613808
    • Wanpeng Li's avatar
      mm/hwpoison: fix page refcount of unknown non LRU page · 4f32be67
      Wanpeng Li authored 
      After trying to drain pages from pagevec/pageset, we try to get reference
count of the page again, however, the reference count of the page is not
reduced if the page is still not on LRU list.

Fix it by adding the put_page() to drop the page reference which is from
__get_any_page().
Signed-off-by: default avatarWanpeng Li <wanpeng.li@hotmail.com>
Acked-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>	[3.9+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      4f32be67
    • Linus Torvalds's avatar
      Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 3670901f
      Linus Torvalds authored 
      Pull timer fix from Ingo Molnar:
 "A single clocksource driver suspend/resume fix"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  clockevents/drivers/sh_cmt: Only perform clocksource suspend/resume if enabled
      3670901f
    • Linus Torvalds's avatar
      Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · b25c6cee
      Linus Torvalds authored 
      Pull perf fixes from Ingo Molnar:
 "Misc fixes: PMU driver corner cases, tooling fixes, and an 'AUX'
  (Intel PT) race related core fix"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel/cqm: Do not access cpu_data() from CPU_UP_PREPARE handler
  perf/x86/intel: Fix memory leak on hot-plug allocation fail
  perf: Fix PERF_EVENT_IOC_PERIOD migration race
  perf: Fix double-free of the AUX buffer
  perf: Fix fasync handling on inherited events
  perf tools: Fix test build error when bindir contains double slash
  perf stat: Fix transaction lenght metrics
  perf: Fix running time accounting
      b25c6cee
    • Linus Torvalds's avatar
      Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 5e5013c6
      Linus Torvalds authored 
      Pull locking fix from Ingo Molnar:
 "A single fix for a locking self-test crash"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/pvqspinlock: Fix kernel panic in locking-selftest
      5e5013c6
    • Linus Torvalds's avatar
      Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux · c6797654
      Linus Torvalds authored 
      Pull drm fixes from Dave Airlie:
 "Back from holidays, found these in the cracks: one nouveau revert, one
  vmwgfx locking fix and a bunch of exynos fixes"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  Revert "drm/nouveau/fifo/gk104: kick channels when deactivating them"
  drm/vmwgfx: Fix execbuf locking issues
  drm/exynos/fimc: fix runtime pm support
  drm/exynos/mixer: always update INT_EN cache
  drm/exynos/mixer: correct vsync configuration sequence
  drm/exynos/mixer: fix interrupt clearing
  drm/exynos/hdmi: fix edid memory leak
  drm/exynos: gsc: fix wrong bitwise operation for swap detection
      c6797654
  17. 13 Aug, 2015 5 commits
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