1. 06 Feb, 2016 6 commits
    • David Gibson's avatar
      memblock: don't mark memblock_phys_mem_size() as __init · 1f1ffb8a
      David Gibson authored
      At the moment memblock_phys_mem_size() is marked as __init, and so is
      discarded after boot.  This is different from most of the memblock
      functions which are marked __init_memblock, and are only discarded after
      boot if memory hotplug is not configured.
      
      To allow for upcoming code which will need memblock_phys_mem_size() in
      the hotplug path, change it from __init to __init_memblock.
      Signed-off-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1f1ffb8a
    • Eric Dumazet's avatar
      dump_stack: avoid potential deadlocks · d7ce3692
      Eric Dumazet authored
      Some servers experienced fatal deadlocks because of a combination of
      bugs, leading to multiple cpus calling dump_stack().
      
      The checksumming bug was fixed in commit 34ae6a1a ("ipv6: update
      skb->csum when CE mark is propagated").
      
      The second problem is a faulty locking in dump_stack()
      
      CPU1 runs in process context and calls dump_stack(), grabs dump_lock.
      
         CPU2 receives a TCP packet under softirq, grabs socket spinlock, and
         call dump_stack() from netdev_rx_csum_fault().
      
         dump_stack() spins on atomic_cmpxchg(&dump_lock, -1, 2), since
         dump_lock is owned by CPU1
      
      While dumping its stack, CPU1 is interrupted by a softirq, and happens
      to process a packet for the TCP socket locked by CPU2.
      
      CPU1 spins forever in spin_lock() : deadlock
      
      Stack trace on CPU1 looked like :
      
          NMI backtrace for cpu 1
          RIP: _raw_spin_lock+0x25/0x30
          ...
          Call Trace:
            <IRQ>
            tcp_v6_rcv+0x243/0x620
            ip6_input_finish+0x11f/0x330
            ip6_input+0x38/0x40
            ip6_rcv_finish+0x3c/0x90
            ipv6_rcv+0x2a9/0x500
            process_backlog+0x461/0xaa0
            net_rx_action+0x147/0x430
            __do_softirq+0x167/0x2d0
            call_softirq+0x1c/0x30
            do_softirq+0x3f/0x80
            irq_exit+0x6e/0xc0
            smp_call_function_single_interrupt+0x35/0x40
            call_function_single_interrupt+0x6a/0x70
            <EOI>
            printk+0x4d/0x4f
            printk_address+0x31/0x33
            print_trace_address+0x33/0x3c
            print_context_stack+0x7f/0x119
            dump_trace+0x26b/0x28e
            show_trace_log_lvl+0x4f/0x5c
            show_stack_log_lvl+0x104/0x113
            show_stack+0x42/0x44
            dump_stack+0x46/0x58
            netdev_rx_csum_fault+0x38/0x3c
            __skb_checksum_complete_head+0x6e/0x80
            __skb_checksum_complete+0x11/0x20
            tcp_rcv_established+0x2bd5/0x2fd0
            tcp_v6_do_rcv+0x13c/0x620
            sk_backlog_rcv+0x15/0x30
            release_sock+0xd2/0x150
            tcp_recvmsg+0x1c1/0xfc0
            inet_recvmsg+0x7d/0x90
            sock_recvmsg+0xaf/0xe0
            ___sys_recvmsg+0x111/0x3b0
            SyS_recvmsg+0x5c/0xb0
            system_call_fastpath+0x16/0x1b
      
      Fixes: b58d9774 ("dump_stack: serialize the output from dump_stack()")
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Cc: Alex Thorlton <athorlton@sgi.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>
      d7ce3692
    • Andrea Arcangeli's avatar
      mm: validate_mm browse_rb SMP race condition · acf128d0
      Andrea Arcangeli authored
      The mmap_sem for reading in validate_mm called from expand_stack is not
      enough to prevent the argumented rbtree rb_subtree_gap information to
      change from under us because expand_stack may be running from other
      threads concurrently which will hold the mmap_sem for reading too.
      
      The argumented rbtree is updated with vma_gap_update under the
      page_table_lock so use it in browse_rb() too to avoid false positives.
      Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
      Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Tested-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Cc: Konstantin Khlebnikov <koct9i@gmail.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      acf128d0
    • Sudip Mukherjee's avatar
      m32r: fix build failure due to SMP and MMU · af1ddcb5
      Sudip Mukherjee authored
      One of the randconfig build failed with the error:
      
        arch/m32r/kernel/smp.c: In function 'smp_flush_tlb_mm':
        arch/m32r/kernel/smp.c:283:20: error: subscripted value is neither array nor pointer nor vector
          mmc = &mm->context[cpu_id];
                            ^
        arch/m32r/kernel/smp.c: In function 'smp_flush_tlb_page':
        arch/m32r/kernel/smp.c:353:20: error: subscripted value is neither array nor pointer nor vector
          mmc = &mm->context[cpu_id];
                            ^
        arch/m32r/kernel/smp.c: In function 'smp_invalidate_interrupt':
        arch/m32r/kernel/smp.c:479:41: error: subscripted value is neither array nor pointer nor vector
          unsigned long *mmc = &flush_mm->context[cpu_id];
      
      It turned out that CONFIG_SMP was defined but CONFIG_MMU was not
      defined.  But arch/m32r/include/asm/mmu.h only defines mm_context_t as
      an array when both CONFIG_SMP and CONFIG_MMU are defined.  And
      arch/m32r/kernel/smp.c is always using context as an array.  So without
      MMU SMP can not work.
      Signed-off-by: default avatarSudip Mukherjee <sudip@vectorindia.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      af1ddcb5
    • Ross Zwisler's avatar
      block: fix pfn_mkwrite() DAX fault handler · 9c5a05bc
      Ross Zwisler authored
      Previously the pfn_mkwrite() fault handler for raw block devices called
      bldev_dax_fault() -> __dax_fault() to do a full DAX page fault.
      
      Really what the pfn_mkwrite() fault handler needs to do is call
      dax_pfn_mkwrite() to make sure that the radix tree entry for the given
      PTE is marked as dirty so that a follow-up fsync or msync call will
      flush it durably to media.
      
      Fixes: 5a023cdb ("block: enable dax for raw block devices")
      Signed-off-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
      Cc: Alexander Viro <viro@zeniv.linux.org.uk>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Dave Chinner <david@fromorbit.com>
      Reviewed-by: default avatarJan Kara <jack@suse.cz>
      Cc: Matthew Wilcox <willy@linux.intel.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9c5a05bc
    • Sasha Levin's avatar
      signals: avoid random wakeups in sigsuspend() · 823dd322
      Sasha Levin authored
      A random wakeup can get us out of sigsuspend() without TIF_SIGPENDING
      being set.
      
      Avoid that by making sure we were signaled, like sys_pause() does.
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      Acked-by: default avatarOleg Nesterov <oleg@redhat.com>
      Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      823dd322
  2. 04 Feb, 2016 3 commits
  3. 03 Feb, 2016 29 commits
  4. 02 Feb, 2016 2 commits