• John David Anglin's avatar
    parisc: Handle case where flush_cache_range is called with no context · 9ef0f88f
    John David Anglin authored
    Just when I had decided that flush_cache_range() was always called with
    a valid context, Helge reported two cases where the
    "BUG_ON(!vma->vm_mm->context);" was hit on the phantom buildd:
    
     kernel BUG at /mnt/sdb6/linux/linux-4.15.4/arch/parisc/kernel/cache.c:587!
     CPU: 1 PID: 3254 Comm: kworker/1:2 Tainted: G D 4.15.0-1-parisc64-smp #1 Debian 4.15.4-1+b1
     Workqueue: events free_ioctx
      IAOQ[0]: flush_cache_range+0x164/0x168
      IAOQ[1]: flush_cache_page+0x0/0x1c8
      RP(r2): unmap_page_range+0xae8/0xb88
     Backtrace:
      [<00000000404a6980>] unmap_page_range+0xae8/0xb88
      [<00000000404a6ae0>] unmap_single_vma+0xc0/0x188
      [<00000000404a6cdc>] zap_page_range_single+0x134/0x1f8
      [<00000000404a702c>] unmap_mapping_range+0x1cc/0x208
      [<0000000040461518>] truncate_pagecache+0x98/0x108
      [<0000000040461624>] truncate_setsize+0x9c/0xb8
      [<00000000405d7f30>] put_aio_ring_file+0x80/0x100
      [<00000000405d803c>] aio_free_ring+0x8c/0x290
      [<00000000405d82c0>] free_ioctx+0x80/0x180
      [<0000000040284e6c>] process_one_work+0x21c/0x668
      [<00000000402854c4>] worker_thread+0x20c/0x778
      [<0000000040291d44>] kthread+0x2d4/0x2e0
      [<0000000040204020>] end_fault_vector+0x20/0xc0
    
    This indicates that we need to handle the no context case in
    flush_cache_range() as we do in flush_cache_mm().
    
    In thinking about this, I realized that we don't need to flush the TLB
    when there is no context.  So, I added context checks to the large flush
    cases in flush_cache_mm() and flush_cache_range().  The large flush case
    occurs frequently in flush_cache_mm() and the change should improve fork
    performance.
    
    The v2 version of this change removes the BUG_ON from flush_cache_page()
    by skipping the TLB flush when there is no context.  I also added code
    to flush the TLB in flush_cache_mm() and flush_cache_range() when we
    have a context that's not current.  Now all three routines handle TLB
    flushes in a similar manner.
    Signed-off-by: default avatarJohn David Anglin <dave.anglin@bell.net>
    Cc: stable@vger.kernel.org # 4.9+
    Signed-off-by: default avatarHelge Deller <deller@gmx.de>
    9ef0f88f
cache.c 17.6 KB