1. 09 Oct, 2020 20 commits
  2. 08 Oct, 2020 20 commits
    • Allen Pais's avatar
      cxgb4: convert tasklets to use new tasklet_setup() API · 0eb484ee
      Allen Pais authored
      In preparation for unconditionally passing the
      struct tasklet_struct pointer to all tasklet
      callbacks, switch to using the new tasklet_setup()
      and from_tasklet() to pass the tasklet pointer explicitly.
      Signed-off-by: default avatarRomain Perier <romain.perier@gmail.com>
      Signed-off-by: default avatarAllen Pais <apais@linux.microsoft.com>
      Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      0eb484ee
    • Johannes Berg's avatar
      ethtool: correct policy for ETHTOOL_MSG_CHANNELS_SET · fd15dd05
      Johannes Berg authored
      This accidentally got wired up to the *get* policy instead
      of the *set* policy, causing operations to be rejected. Fix
      it by wiring up the correct policy instead.
      
      Fixes: 5028588b ("ethtool: wire up set policies to ops")
      Reported-by: default avatarLeon Romanovsky <leon@kernel.org>
      Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
      Tested-by: default avatarLeon Romanovsky <leonro@nvidia.com>
      Reviewed-by: default avatarJakub Kicinski <kuba@kernel.org>
      Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      fd15dd05
    • Johannes Berg's avatar
      ethtool: strset: allow ETHTOOL_A_STRSET_COUNTS_ONLY attr · db972e53
      Johannes Berg authored
      The ETHTOOL_A_STRSET_COUNTS_ONLY flag attribute was previously
      not allowed to be used, but now due to the policy size reduction
      we would access the tb[] array out of bounds since we tried to
      check for the attribute despite it not being accepted.
      
      Fix both issues by adding it correctly to the appropriate policy.
      
      Fixes: ff419afa ("ethtool: trim policy tables")
      Fixes: 71921690 ("ethtool: provide string sets with STRSET_GET request")
      Reported-by: default avatarLeon Romanovsky <leon@kernel.org>
      Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
      Tested-by: default avatarLeon Romanovsky <leonro@nvidia.com>
      Reviewed-by: default avatarJakub Kicinski <kuba@kernel.org>
      Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      db972e53
    • Jakub Kicinski's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net · 9d49aea1
      Jakub Kicinski authored
      Small conflict around locking in rxrpc_process_event() -
      channel_lock moved to bundle in next, while state lock
      needs _bh() from net.
      Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      9d49aea1
    • Linus Torvalds's avatar
      Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost · 3fdd47c3
      Linus Torvalds authored
      Pull vhost fixes from Michael Tsirkin:
       "Some last minute vhost,vdpa fixes.
      
        The last two of them haven't been in next but they do seem kind of
        obvious, very small and safe, fix bugs reported in the field, and they
        are both in a new mlx5 vdpa driver, so it's not like we can introduce
        regressions"
      
      * tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
        vdpa/mlx5: Fix dependency on MLX5_CORE
        vdpa/mlx5: should keep avail_index despite device status
        vhost-vdpa: fix page pinning leakage in error path
        vhost-vdpa: fix vhost_vdpa_map() on error condition
        vhost: Don't call log_access_ok() when using IOTLB
        vhost: Use vhost_get_used_size() in vhost_vring_set_addr()
        vhost: Don't call access_ok() when using IOTLB
        vhost vdpa: fix vhost_vdpa_open error handling
      3fdd47c3
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net · 6288c1d8
      Linus Torvalds authored
      Pull networking fixes from Jakub Kicinski:
       "One more set of fixes from the networking tree:
      
         - add missing input validation in nl80211_del_key(), preventing
           out-of-bounds access
      
         - last minute fix / improvement of a MRP netlink (uAPI) interface
           introduced in 5.9 (current) release
      
         - fix "unresolved symbol" build error under CONFIG_NET w/o
           CONFIG_INET due to missing tcp_timewait_sock and inet_timewait_sock
           BTF.
      
         - fix 32 bit sub-register bounds tracking in the bpf verifier for OR
           case
      
         - tcp: fix receive window update in tcp_add_backlog()
      
         - openvswitch: handle DNAT tuple collision in conntrack-related code
      
         - r8169: wait for potential PHY reset to finish after applying a FW
           file, avoiding unexpected PHY behaviour and failures later on
      
         - mscc: fix tail dropping watermarks for Ocelot switches
      
         - avoid use-after-free in macsec code after a call to the GRO layer
      
         - avoid use-after-free in sctp error paths
      
         - add a device id for Cellient MPL200 WWAN card
      
         - rxrpc fixes:
            - fix the xdr encoding of the contents read from an rxrpc key
            - fix a BUG() for a unsupported encoding type.
            - fix missing _bh lock annotations.
            - fix acceptance handling for an incoming call where the incoming
              call is encrypted.
            - the server token keyring isn't network namespaced - it belongs
              to the server, so there's no need. Namespacing it means that
              request_key() fails to find it.
            - fix a leak of the server keyring"
      
      * git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (21 commits)
        net: usb: qmi_wwan: add Cellient MPL200 card
        macsec: avoid use-after-free in macsec_handle_frame()
        r8169: consider that PHY reset may still be in progress after applying firmware
        openvswitch: handle DNAT tuple collision
        sctp: fix sctp_auth_init_hmacs() error path
        bridge: Netlink interface fix.
        net: wireless: nl80211: fix out-of-bounds access in nl80211_del_key()
        bpf: Fix scalar32_min_max_or bounds tracking
        tcp: fix receive window update in tcp_add_backlog()
        net: usb: rtl8150: set random MAC address when set_ethernet_addr() fails
        mptcp: more DATA FIN fixes
        net: mscc: ocelot: warn when encoding an out-of-bounds watermark value
        net: mscc: ocelot: divide watermark value by 60 when writing to SYS_ATOP
        net: qrtr: ns: Fix the incorrect usage of rcu_read_lock()
        rxrpc: Fix server keyring leak
        rxrpc: The server keyring isn't network-namespaced
        rxrpc: Fix accept on a connection that need securing
        rxrpc: Fix some missing _bh annotations on locking conn->state_lock
        rxrpc: Downgrade the BUG() for unsupported token type in rxrpc_read()
        rxrpc: Fix rxkad token xdr encoding
        ...
      6288c1d8
    • Eli Cohen's avatar
      vdpa/mlx5: Fix dependency on MLX5_CORE · aff90770
      Eli Cohen authored
      Remove propmt for selecting MLX5_VDPA by the user and modify
      MLX5_VDPA_NET to select MLX5_VDPA. Also modify MLX5_VDPA_NET to depend
      on mlx5_core.
      
      This fixes an issue where configuration sets 'y' for MLX5_VDPA_NET while
      MLX5_CORE is compiled as a module causing link errors.
      Reported-by: default avatarkernel test robot <lkp@intel.com>
      Fixes: 1a86b377 ("vdpa/mlx5: Add VDPA driver for supported mlx5 device")s
      Signed-off-by: default avatarEli Cohen <elic@nvidia.com>
      Link: https://lore.kernel.org/r/20201007064011.GA50074@mtl-vdi-166.wap.labs.mlnxSigned-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
      aff90770
    • Si-Wei Liu's avatar
      vdpa/mlx5: should keep avail_index despite device status · 3176e974
      Si-Wei Liu authored
      A VM with mlx5 vDPA has below warnings while being reset:
      
      vhost VQ 0 ring restore failed: -1: Resource temporarily unavailable (11)
      vhost VQ 1 ring restore failed: -1: Resource temporarily unavailable (11)
      
      We should allow userspace emulating the virtio device be
      able to get to vq's avail_index, regardless of vDPA device
      status. Save the index that was last seen when virtq was
      stopped, so that userspace doesn't complain.
      Signed-off-by: default avatarSi-Wei Liu <si-wei.liu@oracle.com>
      Link: https://lore.kernel.org/r/1601583511-15138-1-git-send-email-si-wei.liu@oracle.comSigned-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
      Acked-by: default avatarEli Cohen <elic@nvidia.com>
      3176e974
    • Wilken Gottwalt's avatar
      net: usb: qmi_wwan: add Cellient MPL200 card · 28802e7c
      Wilken Gottwalt authored
      Add usb ids of the Cellient MPL200 card.
      Signed-off-by: default avatarWilken Gottwalt <wilken.gottwalt@mailbox.org>
      Acked-by: default avatarBjørn Mork <bjorn@mork.no>
      Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      28802e7c
    • Eric Dumazet's avatar
      macsec: avoid use-after-free in macsec_handle_frame() · c7cc9200
      Eric Dumazet authored
      De-referencing skb after call to gro_cells_receive() is not allowed.
      We need to fetch skb->len earlier.
      
      Fixes: 5491e7c6 ("macsec: enable GRO and RPS on macsec devices")
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Cc: Paolo Abeni <pabeni@redhat.com>
      Acked-by: default avatarPaolo Abeni <pabeni@redhat.com>
      Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      c7cc9200
    • Heiner Kallweit's avatar
      r8169: consider that PHY reset may still be in progress after applying firmware · 47dda786
      Heiner Kallweit authored
      Some firmware files trigger a PHY soft reset and don't wait for it to
      be finished. PHY register writes directly after applying the firmware
      may fail or provide unexpected results therefore. Fix this by waiting
      for bit BMCR_RESET to be cleared after applying firmware.
      
      There's nothing wrong with the referenced change, it's just that the
      fix will apply cleanly only after this change.
      
      Fixes: 89fbd26c ("r8169: fix firmware not resetting tp->ocp_base")
      Signed-off-by: default avatarHeiner Kallweit <hkallweit1@gmail.com>
      Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      47dda786
    • Dumitru Ceara's avatar
      openvswitch: handle DNAT tuple collision · 8aa7b526
      Dumitru Ceara authored
      With multiple DNAT rules it's possible that after destination
      translation the resulting tuples collide.
      
      For example, two openvswitch flows:
      nw_dst=10.0.0.10,tp_dst=10, actions=ct(commit,table=2,nat(dst=20.0.0.1:20))
      nw_dst=10.0.0.20,tp_dst=10, actions=ct(commit,table=2,nat(dst=20.0.0.1:20))
      
      Assuming two TCP clients initiating the following connections:
      10.0.0.10:5000->10.0.0.10:10
      10.0.0.10:5000->10.0.0.20:10
      
      Both tuples would translate to 10.0.0.10:5000->20.0.0.1:20 causing
      nf_conntrack_confirm() to fail because of tuple collision.
      
      Netfilter handles this case by allocating a null binding for SNAT at
      egress by default.  Perform the same operation in openvswitch for DNAT
      if no explicit SNAT is requested by the user and allocate a null binding
      for SNAT for packets in the "original" direction.
      
      Reported-at: https://bugzilla.redhat.com/1877128Suggested-by: default avatarFlorian Westphal <fw@strlen.de>
      Fixes: 05752523 ("openvswitch: Interface with NAT.")
      Signed-off-by: default avatarDumitru Ceara <dceara@redhat.com>
      Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      8aa7b526
    • Eric Dumazet's avatar
      sctp: fix sctp_auth_init_hmacs() error path · d42ee76e
      Eric Dumazet authored
      After freeing ep->auth_hmacs we have to clear the pointer
      or risk use-after-free as reported by syzbot:
      
      BUG: KASAN: use-after-free in sctp_auth_destroy_hmacs net/sctp/auth.c:509 [inline]
      BUG: KASAN: use-after-free in sctp_auth_destroy_hmacs net/sctp/auth.c:501 [inline]
      BUG: KASAN: use-after-free in sctp_auth_free+0x17e/0x1d0 net/sctp/auth.c:1070
      Read of size 8 at addr ffff8880a8ff52c0 by task syz-executor941/6874
      
      CPU: 0 PID: 6874 Comm: syz-executor941 Not tainted 5.9.0-rc8-syzkaller #0
      Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
      Call Trace:
       __dump_stack lib/dump_stack.c:77 [inline]
       dump_stack+0x198/0x1fd lib/dump_stack.c:118
       print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
       __kasan_report mm/kasan/report.c:513 [inline]
       kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
       sctp_auth_destroy_hmacs net/sctp/auth.c:509 [inline]
       sctp_auth_destroy_hmacs net/sctp/auth.c:501 [inline]
       sctp_auth_free+0x17e/0x1d0 net/sctp/auth.c:1070
       sctp_endpoint_destroy+0x95/0x240 net/sctp/endpointola.c:203
       sctp_endpoint_put net/sctp/endpointola.c:236 [inline]
       sctp_endpoint_free+0xd6/0x110 net/sctp/endpointola.c:183
       sctp_destroy_sock+0x9c/0x3c0 net/sctp/socket.c:4981
       sctp_v6_destroy_sock+0x11/0x20 net/sctp/socket.c:9415
       sk_common_release+0x64/0x390 net/core/sock.c:3254
       sctp_close+0x4ce/0x8b0 net/sctp/socket.c:1533
       inet_release+0x12e/0x280 net/ipv4/af_inet.c:431
       inet6_release+0x4c/0x70 net/ipv6/af_inet6.c:475
       __sock_release+0xcd/0x280 net/socket.c:596
       sock_close+0x18/0x20 net/socket.c:1277
       __fput+0x285/0x920 fs/file_table.c:281
       task_work_run+0xdd/0x190 kernel/task_work.c:141
       exit_task_work include/linux/task_work.h:25 [inline]
       do_exit+0xb7d/0x29f0 kernel/exit.c:806
       do_group_exit+0x125/0x310 kernel/exit.c:903
       __do_sys_exit_group kernel/exit.c:914 [inline]
       __se_sys_exit_group kernel/exit.c:912 [inline]
       __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:912
       do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
       entry_SYSCALL_64_after_hwframe+0x44/0xa9
      RIP: 0033:0x43f278
      Code: Bad RIP value.
      RSP: 002b:00007fffe0995c38 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
      RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043f278
      RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
      RBP: 00000000004bf068 R08: 00000000000000e7 R09: ffffffffffffffd0
      R10: 0000000020000000 R11: 0000000000000246 R12: 0000000000000001
      R13: 00000000006d1180 R14: 0000000000000000 R15: 0000000000000000
      
      Allocated by task 6874:
       kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
       kasan_set_track mm/kasan/common.c:56 [inline]
       __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
       kmem_cache_alloc_trace+0x174/0x300 mm/slab.c:3554
       kmalloc include/linux/slab.h:554 [inline]
       kmalloc_array include/linux/slab.h:593 [inline]
       kcalloc include/linux/slab.h:605 [inline]
       sctp_auth_init_hmacs+0xdb/0x3b0 net/sctp/auth.c:464
       sctp_auth_init+0x8a/0x4a0 net/sctp/auth.c:1049
       sctp_setsockopt_auth_supported net/sctp/socket.c:4354 [inline]
       sctp_setsockopt+0x477e/0x97f0 net/sctp/socket.c:4631
       __sys_setsockopt+0x2db/0x610 net/socket.c:2132
       __do_sys_setsockopt net/socket.c:2143 [inline]
       __se_sys_setsockopt net/socket.c:2140 [inline]
       __x64_sys_setsockopt+0xba/0x150 net/socket.c:2140
       do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
       entry_SYSCALL_64_after_hwframe+0x44/0xa9
      
      Freed by task 6874:
       kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
       kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
       kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
       __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422
       __cache_free mm/slab.c:3422 [inline]
       kfree+0x10e/0x2b0 mm/slab.c:3760
       sctp_auth_destroy_hmacs net/sctp/auth.c:511 [inline]
       sctp_auth_destroy_hmacs net/sctp/auth.c:501 [inline]
       sctp_auth_init_hmacs net/sctp/auth.c:496 [inline]
       sctp_auth_init_hmacs+0x2b7/0x3b0 net/sctp/auth.c:454
       sctp_auth_init+0x8a/0x4a0 net/sctp/auth.c:1049
       sctp_setsockopt_auth_supported net/sctp/socket.c:4354 [inline]
       sctp_setsockopt+0x477e/0x97f0 net/sctp/socket.c:4631
       __sys_setsockopt+0x2db/0x610 net/socket.c:2132
       __do_sys_setsockopt net/socket.c:2143 [inline]
       __se_sys_setsockopt net/socket.c:2140 [inline]
       __x64_sys_setsockopt+0xba/0x150 net/socket.c:2140
       do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
       entry_SYSCALL_64_after_hwframe+0x44/0xa9
      
      Fixes: 1f485649 ("[SCTP]: Implement SCTP-AUTH internals")
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Cc: Vlad Yasevich <vyasevich@gmail.com>
      Cc: Neil Horman <nhorman@tuxdriver.com>
      Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
      Acked-by: default avatarMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
      Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      d42ee76e
    • Jakub Kicinski's avatar
      Merge tag 'mac80211-for-net-2020-10-08' of... · a9e54cb3
      Jakub Kicinski authored
      Merge tag 'mac80211-for-net-2020-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211
      
      Johannes Berg says:
      
      ====================
      pull-request: mac80211 2020-10-08
      
      A single fix for missing input validation in nl80211.
      ====================
      Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      a9e54cb3
    • Jakub Kicinski's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf · cfe90f49
      Jakub Kicinski authored
      Daniel Borkmann says:
      
      ====================
      pull-request: bpf 2020-10-08
      
      The main changes are:
      
      1) Fix "unresolved symbol" build error under CONFIG_NET w/o CONFIG_INET due
         to missing tcp_timewait_sock and inet_timewait_sock BTF, from Yonghong Song.
      
      2) Fix 32 bit sub-register bounds tracking for OR case, from Daniel Borkmann.
      ====================
      Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      cfe90f49
    • Henrik Bjoernlund's avatar
      bridge: Netlink interface fix. · b6c02ef5
      Henrik Bjoernlund authored
      This commit is correcting NETLINK br_fill_ifinfo() to be able to
      handle 'filter_mask' with multiple flags asserted.
      
      Fixes: 36a8e8e2 ("bridge: Extend br_fill_ifinfo to return MPR status")
      Signed-off-by: default avatarHenrik Bjoernlund <henrik.bjoernlund@microchip.com>
      Reviewed-by: default avatarHoratiu Vultur <horatiu.vultur@microchip.com>
      Suggested-by: default avatarNikolay Aleksandrov <nikolay@nvidia.com>
      Tested-by: default avatarHoratiu Vultur <horatiu.vultur@microchip.com>
      Acked-by: default avatarNikolay Aleksandrov <nikolay@nvidia.com>
      Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      b6c02ef5
    • Linus Torvalds's avatar
      Merge tag 'drm-fixes-2020-10-08' of git://anongit.freedesktop.org/drm/drm · 3d006ee4
      Linus Torvalds authored
      Pull drm nouveau fixes from Dave Airlie:
       "Karol found two last minute nouveau fixes, they both fix crashes, the
        TTM one follows what other drivers do already, and the other is for
        bailing on load on unrecognised chipsets.
      
         - fix crash in TTM alloc fail path
      
         - return error earlier for unknown chipsets"
      
      * tag 'drm-fixes-2020-10-08' of git://anongit.freedesktop.org/drm/drm:
        drm/nouveau/mem: guard against NULL pointer access in mem_del
        drm/nouveau/device: return error for unknown chipsets
      3d006ee4
    • Linus Torvalds's avatar
      Merge tag 'exfat-for-5.9-rc9' of git://git.kernel.org/pub/scm/linux/kernel/git/linkinjeon/exfat · b9e3aa2a
      Linus Torvalds authored
      Pull exfat fixes from Namjae Jeon:
      
       - Fix use of uninitialized spinlock on error path
      
       - Fix missing err assignment in exfat_build_inode()
      
      * tag 'exfat-for-5.9-rc9' of git://git.kernel.org/pub/scm/linux/kernel/git/linkinjeon/exfat:
        exfat: fix use of uninitialized spinlock on error path
        exfat: fix pointer error checking
      b9e3aa2a
    • Linus Torvalds's avatar
      Merge tag 'for-linus-5.9b-rc9-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip · 86f0a5fb
      Linus Torvalds authored
      Pull xen fix from Juergen Gross:
       "One fix for a regression when booting as a Xen guest on ARM64
        introduced probably during the 5.9 cycle. It is very low risk as it is
        modifying Xen specific code only.
      
        The exact commit introducing the bug hasn't been identified yet, but
        everything was fine in 5.8 and only in 5.9 some configurations started
        to fail"
      
      * tag 'for-linus-5.9b-rc9-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
        arm/arm64: xen: Fix to convert percpu address to gfn correctly
      86f0a5fb
    • David Howells's avatar
      afs: Fix deadlock between writeback and truncate · ec0fa0b6
      David Howells authored
      The afs filesystem has a lock[*] that it uses to serialise I/O operations
      going to the server (vnode->io_lock), as the server will only perform one
      modification operation at a time on any given file or directory.  This
      prevents the the filesystem from filling up all the call slots to a server
      with calls that aren't going to be executed in parallel anyway, thereby
      allowing operations on other files to obtain slots.
      
        [*] Note that is probably redundant for directories at least since
            i_rwsem is used to serialise directory modifications and
            lookup/reading vs modification.  The server does allow parallel
            non-modification ops, however.
      
      When a file truncation op completes, we truncate the in-memory copy of the
      file to match - but we do it whilst still holding the io_lock, the idea
      being to prevent races with other operations.
      
      However, if writeback starts in a worker thread simultaneously with
      truncation (whilst notify_change() is called with i_rwsem locked, writeback
      pays it no heed), it may manage to set PG_writeback bits on the pages that
      will get truncated before afs_setattr_success() manages to call
      truncate_pagecache().  Truncate will then wait for those pages - whilst
      still inside io_lock:
      
          # cat /proc/8837/stack
          [<0>] wait_on_page_bit_common+0x184/0x1e7
          [<0>] truncate_inode_pages_range+0x37f/0x3eb
          [<0>] truncate_pagecache+0x3c/0x53
          [<0>] afs_setattr_success+0x4d/0x6e
          [<0>] afs_wait_for_operation+0xd8/0x169
          [<0>] afs_do_sync_operation+0x16/0x1f
          [<0>] afs_setattr+0x1fb/0x25d
          [<0>] notify_change+0x2cf/0x3c4
          [<0>] do_truncate+0x7f/0xb2
          [<0>] do_sys_ftruncate+0xd1/0x104
          [<0>] do_syscall_64+0x2d/0x3a
          [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
      
      The writeback operation, however, stalls indefinitely because it needs to
      get the io_lock to proceed:
      
          # cat /proc/5940/stack
          [<0>] afs_get_io_locks+0x58/0x1ae
          [<0>] afs_begin_vnode_operation+0xc7/0xd1
          [<0>] afs_store_data+0x1b2/0x2a3
          [<0>] afs_write_back_from_locked_page+0x418/0x57c
          [<0>] afs_writepages_region+0x196/0x224
          [<0>] afs_writepages+0x74/0x156
          [<0>] do_writepages+0x2d/0x56
          [<0>] __writeback_single_inode+0x84/0x207
          [<0>] writeback_sb_inodes+0x238/0x3cf
          [<0>] __writeback_inodes_wb+0x68/0x9f
          [<0>] wb_writeback+0x145/0x26c
          [<0>] wb_do_writeback+0x16a/0x194
          [<0>] wb_workfn+0x74/0x177
          [<0>] process_one_work+0x174/0x264
          [<0>] worker_thread+0x117/0x1b9
          [<0>] kthread+0xec/0xf1
          [<0>] ret_from_fork+0x1f/0x30
      
      and thus deadlock has occurred.
      
      Note that whilst afs_setattr() calls filemap_write_and_wait(), the fact
      that the caller is holding i_rwsem doesn't preclude more pages being
      dirtied through an mmap'd region.
      
      Fix this by:
      
       (1) Use the vnode validate_lock to mediate access between afs_setattr()
           and afs_writepages():
      
           (a) Exclusively lock validate_lock in afs_setattr() around the whole
           	 RPC operation.
      
           (b) If WB_SYNC_ALL isn't set on entry to afs_writepages(), trying to
           	 shared-lock validate_lock and returning immediately if we couldn't
           	 get it.
      
           (c) If WB_SYNC_ALL is set, wait for the lock.
      
           The validate_lock is also used to validate a file and to zap its cache
           if the file was altered by a third party, so it's probably a good fit
           for this.
      
       (2) Move the truncation outside of the io_lock in setattr, using the same
           hook as is used for local directory editing.
      
           This requires the old i_size to be retained in the operation record as
           we commit the revised status to the inode members inside the io_lock
           still, but we still need to know if we reduced the file size.
      
      Fixes: d2ddc776 ("afs: Overhaul volume and server record caching and fileserver rotation")
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ec0fa0b6