1. 08 10月, 2016 16 次提交
  2. 06 10月, 2016 2 次提交
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    • J
      mm: filemap: don't plant shadow entries without radix tree node · d3798ae8
      Johannes Weiner 提交于
      When the underflow checks were added to workingset_node_shadow_dec(),
      they triggered immediately:
      
        kernel BUG at ./include/linux/swap.h:276!
        invalid opcode: 0000 [#1] SMP
        Modules linked in: isofs usb_storage fuse xt_CHECKSUM ipt_MASQUERADE nf_nat_masquerade_ipv4 tun nf_conntrack_netbios_ns nf_conntrack_broadcast ip6t_REJECT nf_reject_ipv6
         soundcore wmi acpi_als pinctrl_sunrisepoint kfifo_buf tpm_tis industrialio acpi_pad pinctrl_intel tpm_tis_core tpm nfsd auth_rpcgss nfs_acl lockd grace sunrpc dm_crypt
        CPU: 0 PID: 20929 Comm: blkid Not tainted 4.8.0-rc8-00087-gbe67d60b #1
        Hardware name: System manufacturer System Product Name/Z170-K, BIOS 1803 05/06/2016
        task: ffff8faa93ecd940 task.stack: ffff8faa7f478000
        RIP: page_cache_tree_insert+0xf1/0x100
        Call Trace:
          __add_to_page_cache_locked+0x12e/0x270
          add_to_page_cache_lru+0x4e/0xe0
          mpage_readpages+0x112/0x1d0
          blkdev_readpages+0x1d/0x20
          __do_page_cache_readahead+0x1ad/0x290
          force_page_cache_readahead+0xaa/0x100
          page_cache_sync_readahead+0x3f/0x50
          generic_file_read_iter+0x5af/0x740
          blkdev_read_iter+0x35/0x40
          __vfs_read+0xe1/0x130
          vfs_read+0x96/0x130
          SyS_read+0x55/0xc0
          entry_SYSCALL_64_fastpath+0x13/0x8f
        Code: 03 00 48 8b 5d d8 65 48 33 1c 25 28 00 00 00 44 89 e8 75 19 48 83 c4 18 5b 41 5c 41 5d 41 5e 5d c3 0f 0b 41 bd ef ff ff ff eb d7 <0f> 0b e8 88 68 ef ff 0f 1f 84 00
        RIP  page_cache_tree_insert+0xf1/0x100
      
      This is a long-standing bug in the way shadow entries are accounted in
      the radix tree nodes. The shrinker needs to know when radix tree nodes
      contain only shadow entries, no pages, so node->count is split in half
      to count shadows in the upper bits and pages in the lower bits.
      
      Unfortunately, the radix tree implementation doesn't know of this and
      assumes all entries are in node->count. When there is a shadow entry
      directly in root->rnode and the tree is later extended, the radix tree
      implementation will copy that entry into the new node and and bump its
      node->count, i.e. increases the page count bits. Once the shadow gets
      removed and we subtract from the upper counter, node->count underflows
      and triggers the warning. Afterwards, without node->count reaching 0
      again, the radix tree node is leaked.
      
      Limit shadow entries to when we have actual radix tree nodes and can
      count them properly. That means we lose the ability to detect refaults
      from files that had only the first page faulted in at eviction time.
      
      Fixes: 449dd698 ("mm: keep page cache radix tree nodes in check")
      Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
      Reported-and-tested-by: NLinus Torvalds <torvalds@linux-foundation.org>
      Reviewed-by: NJan Kara <jack@suse.cz>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: stable@vger.kernel.org
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d3798ae8
  3. 04 10月, 2016 22 次提交