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Prepare to change target logic #25

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alex opened this issue Oct 13, 2020 · 6 comments
Closed

Prepare to change target logic #25

alex opened this issue Oct 13, 2020 · 6 comments
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• toolchain Related to `rustc`, `bindgen`, `rustdoc`, LLVM, Clippy...

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@alex
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alex commented Oct 13, 2020

If rust-lang/rust#77916 lands in upstream rust, we'll need to change the target we compile with. The new target makes more sense anyways :-)

@alex alex added the • toolchain Related to `rustc`, `bindgen`, `rustdoc`, LLVM, Clippy... label Oct 13, 2020
@ojeda
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ojeda commented Oct 14, 2020

Yeah, although this shows why rustc should not need to have the target to begin with. Unless there is a reason not to, it is cleaner to have it on our end. That eliminates a dependency on a common name, resolves the "naming dispute" FIXME and avoids rustc having to track all possible targets out there. It seems like they might agree, so I supported that view in rust-lang/rust#74247

@Ericson2314
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I'm in now way official over there, to be clear, but yes you state my view exactly! I don't think these sorts of layer violations help anyone.

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ojeda commented Nov 26, 2020

In #28 I go the route of having our own target spec.

ojeda pushed a commit that referenced this issue Nov 28, 2020
Patch series "mm: fix memory to node bad links in sysfs", v3.

Sometimes, firmware may expose interleaved memory layout like this:

 Early memory node ranges
   node   1: [mem 0x0000000000000000-0x000000011fffffff]
   node   2: [mem 0x0000000120000000-0x000000014fffffff]
   node   1: [mem 0x0000000150000000-0x00000001ffffffff]
   node   0: [mem 0x0000000200000000-0x000000048fffffff]
   node   2: [mem 0x0000000490000000-0x00000007ffffffff]

In that case, we can see memory blocks assigned to multiple nodes in
sysfs:

  $ ls -l /sys/devices/system/memory/memory21
  total 0
  lrwxrwxrwx 1 root root     0 Aug 24 05:27 node1 -> ../../node/node1
  lrwxrwxrwx 1 root root     0 Aug 24 05:27 node2 -> ../../node/node2
  -rw-r--r-- 1 root root 65536 Aug 24 05:27 online
  -r--r--r-- 1 root root 65536 Aug 24 05:27 phys_device
  -r--r--r-- 1 root root 65536 Aug 24 05:27 phys_index
  drwxr-xr-x 2 root root     0 Aug 24 05:27 power
  -r--r--r-- 1 root root 65536 Aug 24 05:27 removable
  -rw-r--r-- 1 root root 65536 Aug 24 05:27 state
  lrwxrwxrwx 1 root root     0 Aug 24 05:25 subsystem -> ../../../../bus/memory
  -rw-r--r-- 1 root root 65536 Aug 24 05:25 uevent
  -r--r--r-- 1 root root 65536 Aug 24 05:27 valid_zones

The same applies in the node's directory with a memory21 link in both
the node1 and node2's directory.

This is wrong but doesn't prevent the system to run.  However when
later, one of these memory blocks is hot-unplugged and then hot-plugged,
the system is detecting an inconsistency in the sysfs layout and a
BUG_ON() is raised:

  kernel BUG at /Users/laurent/src/linux-ppc/mm/memory_hotplug.c:1084!
  LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
  Modules linked in: rpadlpar_io rpaphp pseries_rng rng_core vmx_crypto gf128mul binfmt_misc ip_tables x_tables xfs libcrc32c crc32c_vpmsum autofs4
  CPU: 8 PID: 10256 Comm: drmgr Not tainted 5.9.0-rc1+ #25
  Call Trace:
    add_memory_resource+0x23c/0x340 (unreliable)
    __add_memory+0x5c/0xf0
    dlpar_add_lmb+0x1b4/0x500
    dlpar_memory+0x1f8/0xb80
    handle_dlpar_errorlog+0xc0/0x190
    dlpar_store+0x198/0x4a0
    kobj_attr_store+0x30/0x50
    sysfs_kf_write+0x64/0x90
    kernfs_fop_write+0x1b0/0x290
    vfs_write+0xe8/0x290
    ksys_write+0xdc/0x130
    system_call_exception+0x160/0x270
    system_call_common+0xf0/0x27c

This has been seen on PowerPC LPAR.

The root cause of this issue is that when node's memory is registered,
the range used can overlap another node's range, thus the memory block
is registered to multiple nodes in sysfs.

There are two issues here:

 (a) The sysfs memory and node's layouts are broken due to these
     multiple links

 (b) The link errors in link_mem_sections() should not lead to a system
     panic.

To address (a) register_mem_sect_under_node should not rely on the
system state to detect whether the link operation is triggered by a hot
plug operation or not.  This is addressed by the patches 1 and 2 of this
series.

Issue (b) will be addressed separately.

This patch (of 2):

The memmap_context enum is used to detect whether a memory operation is
due to a hot-add operation or happening at boot time.

Make it general to the hotplug operation and rename it as
meminit_context.

There is no functional change introduced by this patch

Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J . Wysocki" <rafael@kernel.org>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200915094143.79181-1-ldufour@linux.ibm.com
Link: https://lkml.kernel.org/r/20200915132624.9723-1-ldufour@linux.ibm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
ojeda pushed a commit that referenced this issue Nov 28, 2020
In register_mem_sect_under_node() the system_state's value is checked to
detect whether the call is made during boot time or during an hot-plug
operation.  Unfortunately, that check against SYSTEM_BOOTING is wrong
because regular memory is registered at SYSTEM_SCHEDULING state.  In
addition, memory hot-plug operation can be triggered at this system
state by the ACPI [1].  So checking against the system state is not
enough.

The consequence is that on system with interleaved node's ranges like this:

 Early memory node ranges
   node   1: [mem 0x0000000000000000-0x000000011fffffff]
   node   2: [mem 0x0000000120000000-0x000000014fffffff]
   node   1: [mem 0x0000000150000000-0x00000001ffffffff]
   node   0: [mem 0x0000000200000000-0x000000048fffffff]
   node   2: [mem 0x0000000490000000-0x00000007ffffffff]

This can be seen on PowerPC LPAR after multiple memory hot-plug and
hot-unplug operations are done.  At the next reboot the node's memory
ranges can be interleaved and since the call to link_mem_sections() is
made in topology_init() while the system is in the SYSTEM_SCHEDULING
state, the node's id is not checked, and the sections registered to
multiple nodes:

  $ ls -l /sys/devices/system/memory/memory21/node*
  total 0
  lrwxrwxrwx 1 root root     0 Aug 24 05:27 node1 -> ../../node/node1
  lrwxrwxrwx 1 root root     0 Aug 24 05:27 node2 -> ../../node/node2

In that case, the system is able to boot but if later one of theses
memory blocks is hot-unplugged and then hot-plugged, the sysfs
inconsistency is detected and this is triggering a BUG_ON():

  kernel BUG at /Users/laurent/src/linux-ppc/mm/memory_hotplug.c:1084!
  Oops: Exception in kernel mode, sig: 5 [#1]
  LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
  Modules linked in: rpadlpar_io rpaphp pseries_rng rng_core vmx_crypto gf128mul binfmt_misc ip_tables x_tables xfs libcrc32c crc32c_vpmsum autofs4
  CPU: 8 PID: 10256 Comm: drmgr Not tainted 5.9.0-rc1+ #25
  Call Trace:
    add_memory_resource+0x23c/0x340 (unreliable)
    __add_memory+0x5c/0xf0
    dlpar_add_lmb+0x1b4/0x500
    dlpar_memory+0x1f8/0xb80
    handle_dlpar_errorlog+0xc0/0x190
    dlpar_store+0x198/0x4a0
    kobj_attr_store+0x30/0x50
    sysfs_kf_write+0x64/0x90
    kernfs_fop_write+0x1b0/0x290
    vfs_write+0xe8/0x290
    ksys_write+0xdc/0x130
    system_call_exception+0x160/0x270
    system_call_common+0xf0/0x27c

This patch addresses the root cause by not relying on the system_state
value to detect whether the call is due to a hot-plug operation.  An
extra parameter is added to link_mem_sections() detailing whether the
operation is due to a hot-plug operation.

[1] According to Oscar Salvador, using this qemu command line, ACPI
memory hotplug operations are raised at SYSTEM_SCHEDULING state:

  $QEMU -enable-kvm -machine pc -smp 4,sockets=4,cores=1,threads=1 -cpu host -monitor pty \
        -m size=$MEM,slots=255,maxmem=4294967296k  \
        -numa node,nodeid=0,cpus=0-3,mem=512 -numa node,nodeid=1,mem=512 \
        -object memory-backend-ram,id=memdimm0,size=134217728 -device pc-dimm,node=0,memdev=memdimm0,id=dimm0,slot=0 \
        -object memory-backend-ram,id=memdimm1,size=134217728 -device pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=1 \
        -object memory-backend-ram,id=memdimm2,size=134217728 -device pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=2 \
        -object memory-backend-ram,id=memdimm3,size=134217728 -device pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=3 \
        -object memory-backend-ram,id=memdimm4,size=134217728 -device pc-dimm,node=1,memdev=memdimm4,id=dimm4,slot=4 \
        -object memory-backend-ram,id=memdimm5,size=134217728 -device pc-dimm,node=1,memdev=memdimm5,id=dimm5,slot=5 \
        -object memory-backend-ram,id=memdimm6,size=134217728 -device pc-dimm,node=1,memdev=memdimm6,id=dimm6,slot=6 \

Fixes: 4fbce63 ("mm/memory_hotplug.c: make register_mem_sect_under_node() a callback of walk_memory_range()")
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200915094143.79181-3-ldufour@linux.ibm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
@ojeda ojeda added the required label Nov 28, 2020
@alex alex modified the milestone: initial-upstream-required Jan 12, 2021
@alex
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alex commented Jan 21, 2021

@ojeda was this obsoleted by the switch to not use cargo?

@ojeda
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ojeda commented Jan 21, 2021

It was obsoleted by #28 given we use custom targets, although I didn't close this given the discussions are ongoing e.g. see the overview I wrote yesterday at rust-lang/rust#71009. But changing the title or closing this and creating a new issue makes sense.

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alex commented Jan 22, 2021

I'm going to close this, given the precise original reason I filed it for has been obviated.

@alex alex closed this as completed Jan 22, 2021
ojeda pushed a commit that referenced this issue Mar 21, 2021
After commit 997acaf (lockdep: report broken irq restoration), the guest
splatting below during boot:

 raw_local_irq_restore() called with IRQs enabled
 WARNING: CPU: 1 PID: 169 at kernel/locking/irqflag-debug.c:10 warn_bogus_irq_restore+0x26/0x30
 Modules linked in: hid_generic usbhid hid
 CPU: 1 PID: 169 Comm: systemd-udevd Not tainted 5.11.0+ #25
 RIP: 0010:warn_bogus_irq_restore+0x26/0x30
 Call Trace:
  kvm_wait+0x76/0x90
  __pv_queued_spin_lock_slowpath+0x285/0x2e0
  do_raw_spin_lock+0xc9/0xd0
  _raw_spin_lock+0x59/0x70
  lockref_get_not_dead+0xf/0x50
  __legitimize_path+0x31/0x60
  legitimize_root+0x37/0x50
  try_to_unlazy_next+0x7f/0x1d0
  lookup_fast+0xb0/0x170
  path_openat+0x165/0x9b0
  do_filp_open+0x99/0x110
  do_sys_openat2+0x1f1/0x2e0
  do_sys_open+0x5c/0x80
  __x64_sys_open+0x21/0x30
  do_syscall_64+0x32/0x50
  entry_SYSCALL_64_after_hwframe+0x44/0xae

The new consistency checking,  expects local_irq_save() and
local_irq_restore() to be paired and sanely nested, and therefore expects
local_irq_restore() to be called with irqs disabled.
The irqflags handling in kvm_wait() which ends up doing:

	local_irq_save(flags);
	safe_halt();
	local_irq_restore(flags);

instead triggers it.  This patch fixes it by using
local_irq_disable()/enable() directly.

Cc: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1615791328-2735-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
ojeda pushed a commit that referenced this issue Jan 10, 2022
After commit d3256ef ("veth: allow enabling NAPI even without XDP"),
if GRO is enabled on a veth device and TSO is disabled on the peer
device, TCP skbs will go through the NAPI callback. If there is no XDP
program attached, the veth code does not perform any share check, and
shared/cloned skbs could enter the GRO engine.

Ignat reported a BUG triggered later-on due to the above condition:

[   53.970529][    C1] kernel BUG at net/core/skbuff.c:3574!
[   53.981755][    C1] invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
[   53.982634][    C1] CPU: 1 PID: 19 Comm: ksoftirqd/1 Not tainted 5.16.0-rc5+ #25
[   53.982634][    C1] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
[   53.982634][    C1] RIP: 0010:skb_shift+0x13ef/0x23b0
[   53.982634][    C1] Code: ea 03 0f b6 04 02 48 89 fa 83 e2 07 38 d0
7f 08 84 c0 0f 85 41 0c 00 00 41 80 7f 02 00 4d 8d b5 d0 00 00 00 0f
85 74 f5 ff ff <0f> 0b 4d 8d 77 20 be 04 00 00 00 4c 89 44 24 78 4c 89
f7 4c 89 8c
[   53.982634][    C1] RSP: 0018:ffff8881008f7008 EFLAGS: 00010246
[   53.982634][    C1] RAX: 0000000000000000 RBX: ffff8881180b4c80 RCX: 0000000000000000
[   53.982634][    C1] RDX: 0000000000000002 RSI: ffff8881180b4d3c RDI: ffff88810bc9cac2
[   53.982634][    C1] RBP: ffff8881008f70b8 R08: ffff8881180b4cf4 R09: ffff8881180b4cf0
[   53.982634][    C1] R10: ffffed1022999e5c R11: 0000000000000002 R12: 0000000000000590
[   53.982634][    C1] R13: ffff88810f940c80 R14: ffff88810f940d50 R15: ffff88810bc9cac0
[   53.982634][    C1] FS:  0000000000000000(0000) GS:ffff888235880000(0000) knlGS:0000000000000000
[   53.982634][    C1] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   53.982634][    C1] CR2: 00007ff5f9b86680 CR3: 0000000108ce8004 CR4: 0000000000170ee0
[   53.982634][    C1] Call Trace:
[   53.982634][    C1]  <TASK>
[   53.982634][    C1]  tcp_sacktag_walk+0xaba/0x18e0
[   53.982634][    C1]  tcp_sacktag_write_queue+0xe7b/0x3460
[   53.982634][    C1]  tcp_ack+0x2666/0x54b0
[   53.982634][    C1]  tcp_rcv_established+0x4d9/0x20f0
[   53.982634][    C1]  tcp_v4_do_rcv+0x551/0x810
[   53.982634][    C1]  tcp_v4_rcv+0x22ed/0x2ed0
[   53.982634][    C1]  ip_protocol_deliver_rcu+0x96/0xaf0
[   53.982634][    C1]  ip_local_deliver_finish+0x1e0/0x2f0
[   53.982634][    C1]  ip_sublist_rcv_finish+0x211/0x440
[   53.982634][    C1]  ip_list_rcv_finish.constprop.0+0x424/0x660
[   53.982634][    C1]  ip_list_rcv+0x2c8/0x410
[   53.982634][    C1]  __netif_receive_skb_list_core+0x65c/0x910
[   53.982634][    C1]  netif_receive_skb_list_internal+0x5f9/0xcb0
[   53.982634][    C1]  napi_complete_done+0x188/0x6e0
[   53.982634][    C1]  gro_cell_poll+0x10c/0x1d0
[   53.982634][    C1]  __napi_poll+0xa1/0x530
[   53.982634][    C1]  net_rx_action+0x567/0x1270
[   53.982634][    C1]  __do_softirq+0x28a/0x9ba
[   53.982634][    C1]  run_ksoftirqd+0x32/0x60
[   53.982634][    C1]  smpboot_thread_fn+0x559/0x8c0
[   53.982634][    C1]  kthread+0x3b9/0x490
[   53.982634][    C1]  ret_from_fork+0x22/0x30
[   53.982634][    C1]  </TASK>

Address the issue by skipping the GRO stage for shared or cloned skbs.
To reduce the chance of OoO, try to unclone the skbs before giving up.

v1 -> v2:
 - use avoid skb_copy and fallback to netif_receive_skb  - Eric

Reported-by: Ignat Korchagin <ignat@cloudflare.com>
Fixes: d3256ef ("veth: allow enabling NAPI even without XDP")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Tested-by: Ignat Korchagin <ignat@cloudflare.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/b5f61c5602aab01bac8d711d8d1bfab0a4817db7.1640197544.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
ojeda pushed a commit that referenced this issue Feb 28, 2022
When bringing down the netdevice or system shutdown, a panic can be
triggered while accessing the sysfs path because the device is already
removed.

    [  755.549084] mlx5_core 0000:12:00.1: Shutdown was called
    [  756.404455] mlx5_core 0000:12:00.0: Shutdown was called
    ...
    [  757.937260] BUG: unable to handle kernel NULL pointer dereference at           (null)
    [  758.031397] IP: [<ffffffff8ee11acb>] dma_pool_alloc+0x1ab/0x280

    crash> bt
    ...
    PID: 12649  TASK: ffff8924108f2100  CPU: 1   COMMAND: "amsd"
    ...
     #9 [ffff89240e1a38b0] page_fault at ffffffff8f38c778
        [exception RIP: dma_pool_alloc+0x1ab]
        RIP: ffffffff8ee11acb  RSP: ffff89240e1a3968  RFLAGS: 00010046
        RAX: 0000000000000246  RBX: ffff89243d874100  RCX: 0000000000001000
        RDX: 0000000000000000  RSI: 0000000000000246  RDI: ffff89243d874090
        RBP: ffff89240e1a39c0   R8: 000000000001f080   R9: ffff8905ffc03c00
        R10: ffffffffc04680d4  R11: ffffffff8edde9fd  R12: 00000000000080d0
        R13: ffff89243d874090  R14: ffff89243d874080  R15: 0000000000000000
        ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
    #10 [ffff89240e1a39c8] mlx5_alloc_cmd_msg at ffffffffc04680f3 [mlx5_core]
    #11 [ffff89240e1a3a18] cmd_exec at ffffffffc046ad62 [mlx5_core]
    #12 [ffff89240e1a3ab8] mlx5_cmd_exec at ffffffffc046b4fb [mlx5_core]
    #13 [ffff89240e1a3ae8] mlx5_core_access_reg at ffffffffc0475434 [mlx5_core]
    #14 [ffff89240e1a3b40] mlx5e_get_fec_caps at ffffffffc04a7348 [mlx5_core]
    #15 [ffff89240e1a3bb0] get_fec_supported_advertised at ffffffffc04992bf [mlx5_core]
    #16 [ffff89240e1a3c08] mlx5e_get_link_ksettings at ffffffffc049ab36 [mlx5_core]
    #17 [ffff89240e1a3ce8] __ethtool_get_link_ksettings at ffffffff8f25db46
    #18 [ffff89240e1a3d48] speed_show at ffffffff8f277208
    #19 [ffff89240e1a3dd8] dev_attr_show at ffffffff8f0b70e3
    #20 [ffff89240e1a3df8] sysfs_kf_seq_show at ffffffff8eedbedf
    #21 [ffff89240e1a3e18] kernfs_seq_show at ffffffff8eeda596
    #22 [ffff89240e1a3e28] seq_read at ffffffff8ee76d10
    #23 [ffff89240e1a3e98] kernfs_fop_read at ffffffff8eedaef5
    #24 [ffff89240e1a3ed8] vfs_read at ffffffff8ee4e3ff
    #25 [ffff89240e1a3f08] sys_read at ffffffff8ee4f27f
    #26 [ffff89240e1a3f50] system_call_fastpath at ffffffff8f395f92

    crash> net_device.state ffff89443b0c0000
      state = 0x5  (__LINK_STATE_START| __LINK_STATE_NOCARRIER)

To prevent this scenario, we also make sure that the netdevice is present.

Signed-off-by: suresh kumar <suresh2514@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ojeda pushed a commit that referenced this issue Dec 4, 2022
UBSAN complains about array-index-out-of-bounds:
[ 1.980703] kernel: UBSAN: array-index-out-of-bounds in /build/linux-9H675w/linux-5.15.0/drivers/ata/libahci.c:968:41
[ 1.980709] kernel: index 15 is out of range for type 'ahci_em_priv [8]'
[ 1.980713] kernel: CPU: 0 PID: 209 Comm: scsi_eh_8 Not tainted 5.15.0-25-generic #25-Ubuntu
[ 1.980716] kernel: Hardware name: System manufacturer System Product Name/P5Q3, BIOS 1102 06/11/2010
[ 1.980718] kernel: Call Trace:
[ 1.980721] kernel: <TASK>
[ 1.980723] kernel: show_stack+0x52/0x58
[ 1.980729] kernel: dump_stack_lvl+0x4a/0x5f
[ 1.980734] kernel: dump_stack+0x10/0x12
[ 1.980736] kernel: ubsan_epilogue+0x9/0x45
[ 1.980739] kernel: __ubsan_handle_out_of_bounds.cold+0x44/0x49
[ 1.980742] kernel: ahci_qc_issue+0x166/0x170 [libahci]
[ 1.980748] kernel: ata_qc_issue+0x135/0x240
[ 1.980752] kernel: ata_exec_internal_sg+0x2c4/0x580
[ 1.980754] kernel: ? vprintk_default+0x1d/0x20
[ 1.980759] kernel: ata_exec_internal+0x67/0xa0
[ 1.980762] kernel: sata_pmp_read+0x8d/0xc0
[ 1.980765] kernel: sata_pmp_read_gscr+0x3c/0x90
[ 1.980768] kernel: sata_pmp_attach+0x8b/0x310
[ 1.980771] kernel: ata_eh_revalidate_and_attach+0x28c/0x4b0
[ 1.980775] kernel: ata_eh_recover+0x6b6/0xb30
[ 1.980778] kernel: ? ahci_do_hardreset+0x180/0x180 [libahci]
[ 1.980783] kernel: ? ahci_stop_engine+0xb0/0xb0 [libahci]
[ 1.980787] kernel: ? ahci_do_softreset+0x290/0x290 [libahci]
[ 1.980792] kernel: ? trace_event_raw_event_ata_eh_link_autopsy_qc+0xe0/0xe0
[ 1.980795] kernel: sata_pmp_eh_recover.isra.0+0x214/0x560
[ 1.980799] kernel: sata_pmp_error_handler+0x23/0x40
[ 1.980802] kernel: ahci_error_handler+0x43/0x80 [libahci]
[ 1.980806] kernel: ata_scsi_port_error_handler+0x2b1/0x600
[ 1.980810] kernel: ata_scsi_error+0x9c/0xd0
[ 1.980813] kernel: scsi_error_handler+0xa1/0x180
[ 1.980817] kernel: ? scsi_unjam_host+0x1c0/0x1c0
[ 1.980820] kernel: kthread+0x12a/0x150
[ 1.980823] kernel: ? set_kthread_struct+0x50/0x50
[ 1.980826] kernel: ret_from_fork+0x22/0x30
[ 1.980831] kernel: </TASK>

This happens because sata_pmp_init_links() initialize link->pmp up to
SATA_PMP_MAX_PORTS while em_priv is declared as 8 elements array.

I can't find the maximum Enclosure Management ports specified in AHCI
spec v1.3.1, but "12.2.1 LED message type" states that "Port Multiplier
Information" can utilize 4 bits, which implies it can support up to 16
ports. Hence, use SATA_PMP_MAX_PORTS as EM_MAX_SLOTS to resolve the
issue.

BugLink: https://bugs.launchpad.net/bugs/1970074
Cc: stable@vger.kernel.org
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
ojeda pushed a commit that referenced this issue Dec 4, 2022
…der memory pressure

When destroying a queue, when calling sock_release, the network stack
might need to allocate an skb to send a FIN/RST. When that happens
during memory pressure, there is a need to reclaim memory, which
in turn may ask the nvme-tcp device to write out dirty pages, however
this is not possible due to a ctrl teardown that is going on.

Set PF_MEMALLOC to the task that releases the socket to grant access
to PF_MEMALLOC reserves. In addition, do the same for the nvme-tcp
thread as this may also originate from the swap itself and should
be more resilient to memory pressure situations.

This fixes the following lockdep complaint:
--
======================================================
 WARNING: possible circular locking dependency detected
 6.0.0-rc2+ #25 Tainted: G        W
 ------------------------------------------------------
 kswapd0/92 is trying to acquire lock:
 ffff888114003240 (sk_lock-AF_INET-NVME){+.+.}-{0:0}, at: tcp_sendpage+0x23/0xa0

 but task is already holding lock:
 ffffffff97e95ca0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x987/0x10d0

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #1 (fs_reclaim){+.+.}-{0:0}:
        fs_reclaim_acquire+0x11e/0x160
        kmem_cache_alloc_node+0x44/0x530
        __alloc_skb+0x158/0x230
        tcp_send_active_reset+0x7e/0x730
        tcp_disconnect+0x1272/0x1ae0
        __tcp_close+0x707/0xd90
        tcp_close+0x26/0x80
        inet_release+0xfa/0x220
        sock_release+0x85/0x1a0
        nvme_tcp_free_queue+0x1fd/0x470 [nvme_tcp]
        nvme_do_delete_ctrl+0x130/0x13d [nvme_core]
        nvme_sysfs_delete.cold+0x8/0xd [nvme_core]
        kernfs_fop_write_iter+0x356/0x530
        vfs_write+0x4e8/0xce0
        ksys_write+0xfd/0x1d0
        do_syscall_64+0x58/0x80
        entry_SYSCALL_64_after_hwframe+0x63/0xcd

 -> #0 (sk_lock-AF_INET-NVME){+.+.}-{0:0}:
        __lock_acquire+0x2a0c/0x5690
        lock_acquire+0x18e/0x4f0
        lock_sock_nested+0x37/0xc0
        tcp_sendpage+0x23/0xa0
        inet_sendpage+0xad/0x120
        kernel_sendpage+0x156/0x440
        nvme_tcp_try_send+0x48a/0x2630 [nvme_tcp]
        nvme_tcp_queue_rq+0xefb/0x17e0 [nvme_tcp]
        __blk_mq_try_issue_directly+0x452/0x660
        blk_mq_plug_issue_direct.constprop.0+0x207/0x700
        blk_mq_flush_plug_list+0x6f5/0xc70
        __blk_flush_plug+0x264/0x410
        blk_finish_plug+0x4b/0xa0
        shrink_lruvec+0x1263/0x1ea0
        shrink_node+0x736/0x1a80
        balance_pgdat+0x740/0x10d0
        kswapd+0x5f2/0xaf0
        kthread+0x256/0x2f0
        ret_from_fork+0x1f/0x30

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(fs_reclaim);
                               lock(sk_lock-AF_INET-NVME);
                               lock(fs_reclaim);
  lock(sk_lock-AF_INET-NVME);

 *** DEADLOCK ***

3 locks held by kswapd0/92:
 #0: ffffffff97e95ca0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x987/0x10d0
 #1: ffff88811f21b0b0 (q->srcu){....}-{0:0}, at: blk_mq_flush_plug_list+0x6b3/0xc70
 #2: ffff888170b11470 (&queue->send_mutex){+.+.}-{3:3}, at: nvme_tcp_queue_rq+0xeb9/0x17e0 [nvme_tcp]

Fixes: 3f2304f ("nvme-tcp: add NVMe over TCP host driver")
Reported-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Tested-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
ojeda pushed a commit that referenced this issue Dec 4, 2022
`hostname` needs to be set as null-pointer after free in
`cifs_put_tcp_session` function, or when `cifsd` thread attempts
to resolve hostname and reconnect the host, the thread would deref
the invalid pointer.

Here is one of practical backtrace examples as reference:

Task 477
---------------------------
 do_mount
  path_mount
   do_new_mount
    vfs_get_tree
     smb3_get_tree
      smb3_get_tree_common
       cifs_smb3_do_mount
        cifs_mount
         mount_put_conns
          cifs_put_tcp_session
          --> kfree(server->hostname)

cifsd
---------------------------
 kthread
  cifs_demultiplex_thread
   cifs_reconnect
    reconn_set_ipaddr_from_hostname
    --> if (!server->hostname)
    --> if (server->hostname[0] == '\0')  // !! UAF fault here

CIFS: VFS: cifs_mount failed w/return code = -112
mount error(112): Host is down
BUG: KASAN: use-after-free in reconn_set_ipaddr_from_hostname+0x2ba/0x310
Read of size 1 at addr ffff888108f35380 by task cifsd/480
CPU: 2 PID: 480 Comm: cifsd Not tainted 6.1.0-rc2-00106-gf705792f89dd-dirty #25
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x68/0x85
 print_report+0x16c/0x4a3
 kasan_report+0x95/0x190
 reconn_set_ipaddr_from_hostname+0x2ba/0x310
 __cifs_reconnect.part.0+0x241/0x800
 cifs_reconnect+0x65f/0xb60
 cifs_demultiplex_thread+0x1570/0x2570
 kthread+0x2c5/0x380
 ret_from_fork+0x22/0x30
 </TASK>
Allocated by task 477:
 kasan_save_stack+0x1e/0x40
 kasan_set_track+0x21/0x30
 __kasan_kmalloc+0x7e/0x90
 __kmalloc_node_track_caller+0x52/0x1b0
 kstrdup+0x3b/0x70
 cifs_get_tcp_session+0xbc/0x19b0
 mount_get_conns+0xa9/0x10c0
 cifs_mount+0xdf/0x1970
 cifs_smb3_do_mount+0x295/0x1660
 smb3_get_tree+0x352/0x5e0
 vfs_get_tree+0x8e/0x2e0
 path_mount+0xf8c/0x1990
 do_mount+0xee/0x110
 __x64_sys_mount+0x14b/0x1f0
 do_syscall_64+0x3b/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
Freed by task 477:
 kasan_save_stack+0x1e/0x40
 kasan_set_track+0x21/0x30
 kasan_save_free_info+0x2a/0x50
 __kasan_slab_free+0x10a/0x190
 __kmem_cache_free+0xca/0x3f0
 cifs_put_tcp_session+0x30c/0x450
 cifs_mount+0xf95/0x1970
 cifs_smb3_do_mount+0x295/0x1660
 smb3_get_tree+0x352/0x5e0
 vfs_get_tree+0x8e/0x2e0
 path_mount+0xf8c/0x1990
 do_mount+0xee/0x110
 __x64_sys_mount+0x14b/0x1f0
 do_syscall_64+0x3b/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
The buggy address belongs to the object at ffff888108f35380
 which belongs to the cache kmalloc-16 of size 16
The buggy address is located 0 bytes inside of
 16-byte region [ffff888108f35380, ffff888108f35390)
The buggy address belongs to the physical page:
page:00000000333f8e58 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888108f350e0 pfn:0x108f35
flags: 0x200000000000200(slab|node=0|zone=2)
raw: 0200000000000200 0000000000000000 dead000000000122 ffff8881000423c0
raw: ffff888108f350e0 000000008080007a 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
 ffff888108f35280: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc
 ffff888108f35300: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc
>ffff888108f35380: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc
                   ^
 ffff888108f35400: fa fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888108f35480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

Fixes: 7be3248 ("cifs: To match file servers, make sure the server hostname matches")
Signed-off-by: Zeng Heng <zengheng4@huawei.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
fbq pushed a commit that referenced this issue Sep 25, 2023
The following processes run into a deadlock. CPU 41 was waiting for CPU 29
to handle a CSD request while holding spinlock "crashdump_lock", but CPU 29
was hung by that spinlock with IRQs disabled.

  PID: 17360    TASK: ffff95c1090c5c40  CPU: 41  COMMAND: "mrdiagd"
  !# 0 [ffffb80edbf37b58] __read_once_size at ffffffff9b871a40 include/linux/compiler.h:185:0
  !# 1 [ffffb80edbf37b58] atomic_read at ffffffff9b871a40 arch/x86/include/asm/atomic.h:27:0
  !# 2 [ffffb80edbf37b58] dump_stack at ffffffff9b871a40 lib/dump_stack.c:54:0
   # 3 [ffffb80edbf37b78] csd_lock_wait_toolong at ffffffff9b131ad5 kernel/smp.c:364:0
   # 4 [ffffb80edbf37b78] __csd_lock_wait at ffffffff9b131ad5 kernel/smp.c:384:0
   # 5 [ffffb80edbf37bf8] csd_lock_wait at ffffffff9b13267a kernel/smp.c:394:0
   # 6 [ffffb80edbf37bf8] smp_call_function_many at ffffffff9b13267a kernel/smp.c:843:0
   # 7 [ffffb80edbf37c50] smp_call_function at ffffffff9b13279d kernel/smp.c:867:0
   # 8 [ffffb80edbf37c50] on_each_cpu at ffffffff9b13279d kernel/smp.c:976:0
   # 9 [ffffb80edbf37c78] flush_tlb_kernel_range at ffffffff9b085c4b arch/x86/mm/tlb.c:742:0
   #10 [ffffb80edbf37cb8] __purge_vmap_area_lazy at ffffffff9b23a1e0 mm/vmalloc.c:701:0
   #11 [ffffb80edbf37ce0] try_purge_vmap_area_lazy at ffffffff9b23a2cc mm/vmalloc.c:722:0
   #12 [ffffb80edbf37ce0] free_vmap_area_noflush at ffffffff9b23a2cc mm/vmalloc.c:754:0
   #13 [ffffb80edbf37cf8] free_unmap_vmap_area at ffffffff9b23bb3b mm/vmalloc.c:764:0
   #14 [ffffb80edbf37cf8] remove_vm_area at ffffffff9b23bb3b mm/vmalloc.c:1509:0
   #15 [ffffb80edbf37d18] __vunmap at ffffffff9b23bb8a mm/vmalloc.c:1537:0
   #16 [ffffb80edbf37d40] vfree at ffffffff9b23bc85 mm/vmalloc.c:1612:0
   #17 [ffffb80edbf37d58] megasas_free_host_crash_buffer [megaraid_sas] at ffffffffc020b7f2 drivers/scsi/megaraid/megaraid_sas_fusion.c:3932:0
   #18 [ffffb80edbf37d80] fw_crash_state_store [megaraid_sas] at ffffffffc01f804d drivers/scsi/megaraid/megaraid_sas_base.c:3291:0
   #19 [ffffb80edbf37dc0] dev_attr_store at ffffffff9b56dd7b drivers/base/core.c:758:0
   #20 [ffffb80edbf37dd0] sysfs_kf_write at ffffffff9b326acf fs/sysfs/file.c:144:0
   #21 [ffffb80edbf37de0] kernfs_fop_write at ffffffff9b325fd4 fs/kernfs/file.c:316:0
   #22 [ffffb80edbf37e20] __vfs_write at ffffffff9b29418a fs/read_write.c:480:0
   #23 [ffffb80edbf37ea8] vfs_write at ffffffff9b294462 fs/read_write.c:544:0
   #24 [ffffb80edbf37ee8] SYSC_write at ffffffff9b2946ec fs/read_write.c:590:0
   #25 [ffffb80edbf37ee8] SyS_write at ffffffff9b2946ec fs/read_write.c:582:0
   #26 [ffffb80edbf37f30] do_syscall_64 at ffffffff9b003ca9 arch/x86/entry/common.c:298:0
   #27 [ffffb80edbf37f58] entry_SYSCALL_64 at ffffffff9ba001b1 arch/x86/entry/entry_64.S:238:0

  PID: 17355    TASK: ffff95c1090c3d80  CPU: 29  COMMAND: "mrdiagd"
  !# 0 [ffffb80f2d3c7d30] __read_once_size at ffffffff9b0f2ab0 include/linux/compiler.h:185:0
  !# 1 [ffffb80f2d3c7d30] native_queued_spin_lock_slowpath at ffffffff9b0f2ab0 kernel/locking/qspinlock.c:368:0
   # 2 [ffffb80f2d3c7d58] pv_queued_spin_lock_slowpath at ffffffff9b0f244b arch/x86/include/asm/paravirt.h:674:0
   # 3 [ffffb80f2d3c7d58] queued_spin_lock_slowpath at ffffffff9b0f244b arch/x86/include/asm/qspinlock.h:53:0
   # 4 [ffffb80f2d3c7d68] queued_spin_lock at ffffffff9b8961a6 include/asm-generic/qspinlock.h:90:0
   # 5 [ffffb80f2d3c7d68] do_raw_spin_lock_flags at ffffffff9b8961a6 include/linux/spinlock.h:173:0
   # 6 [ffffb80f2d3c7d68] __raw_spin_lock_irqsave at ffffffff9b8961a6 include/linux/spinlock_api_smp.h:122:0
   # 7 [ffffb80f2d3c7d68] _raw_spin_lock_irqsave at ffffffff9b8961a6 kernel/locking/spinlock.c:160:0
   # 8 [ffffb80f2d3c7d88] fw_crash_buffer_store [megaraid_sas] at ffffffffc01f8129 drivers/scsi/megaraid/megaraid_sas_base.c:3205:0
   # 9 [ffffb80f2d3c7dc0] dev_attr_store at ffffffff9b56dd7b drivers/base/core.c:758:0
   #10 [ffffb80f2d3c7dd0] sysfs_kf_write at ffffffff9b326acf fs/sysfs/file.c:144:0
   #11 [ffffb80f2d3c7de0] kernfs_fop_write at ffffffff9b325fd4 fs/kernfs/file.c:316:0
   #12 [ffffb80f2d3c7e20] __vfs_write at ffffffff9b29418a fs/read_write.c:480:0
   #13 [ffffb80f2d3c7ea8] vfs_write at ffffffff9b294462 fs/read_write.c:544:0
   #14 [ffffb80f2d3c7ee8] SYSC_write at ffffffff9b2946ec fs/read_write.c:590:0
   #15 [ffffb80f2d3c7ee8] SyS_write at ffffffff9b2946ec fs/read_write.c:582:0
   #16 [ffffb80f2d3c7f30] do_syscall_64 at ffffffff9b003ca9 arch/x86/entry/common.c:298:0
   #17 [ffffb80f2d3c7f58] entry_SYSCALL_64 at ffffffff9ba001b1 arch/x86/entry/entry_64.S:238:0

The lock is used to synchronize different sysfs operations, it doesn't
protect any resource that will be touched by an interrupt. Consequently
it's not required to disable IRQs. Replace the spinlock with a mutex to fix
the deadlock.

Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Link: https://lore.kernel.org/r/20230828221018.19471-1-junxiao.bi@oracle.com
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
ojeda pushed a commit that referenced this issue May 27, 2024
Klara Modin reported warnings for a kernel configured with BPF_JIT but
without MODULES:

[   44.131296] Trying to vfree() bad address (000000004a17c299)
[   44.138024] WARNING: CPU: 1 PID: 193 at mm/vmalloc.c:3189 remove_vm_area (mm/vmalloc.c:3189 (discriminator 1))
[   44.146675] CPU: 1 PID: 193 Comm: kworker/1:2 Tainted: G      D W          6.9.0-01786-g2c9e5d4a0082 #25
[   44.158229] Hardware name: Raspberry Pi 3 Model B (DT)
[   44.164433] Workqueue: events bpf_prog_free_deferred
[   44.170492] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[   44.178601] pc : remove_vm_area (mm/vmalloc.c:3189 (discriminator 1))
[   44.183705] lr : remove_vm_area (mm/vmalloc.c:3189 (discriminator 1))
[   44.188772] sp : ffff800082a13c70
[   44.193112] x29: ffff800082a13c70 x28: 0000000000000000 x27: 0000000000000000
[   44.201384] x26: 0000000000000000 x25: ffff00003a44efa0 x24: 00000000d4202000
[   44.209658] x23: ffff800081223dd0 x22: ffff00003a198a40 x21: ffff8000814dd880
[   44.217924] x20: 00000000d4202000 x19: ffff8000814dd880 x18: 0000000000000006
[   44.226206] x17: 0000000000000000 x16: 0000000000000020 x15: 0000000000000002
[   44.234460] x14: ffff8000811a6370 x13: 0000000020000000 x12: 0000000000000000
[   44.242710] x11: ffff8000811a6370 x10: 0000000000000144 x9 : ffff8000811fe370
[   44.250959] x8 : 0000000000017fe8 x7 : 00000000fffff000 x6 : ffff8000811fe370
[   44.259206] x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000
[   44.267457] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff000002203240
[   44.275703] Call trace:
[   44.279158] remove_vm_area (mm/vmalloc.c:3189 (discriminator 1))
[   44.283858] vfree (mm/vmalloc.c:3322)
[   44.287835] execmem_free (mm/execmem.c:70)
[   44.292347] bpf_jit_free_exec+0x10/0x1c
[   44.297283] bpf_prog_pack_free (kernel/bpf/core.c:1006)
[   44.302457] bpf_jit_binary_pack_free (kernel/bpf/core.c:1195)
[   44.307951] bpf_jit_free (include/linux/filter.h:1083 arch/arm64/net/bpf_jit_comp.c:2474)
[   44.312342] bpf_prog_free_deferred (kernel/bpf/core.c:2785)
[   44.317785] process_one_work (kernel/workqueue.c:3273)
[   44.322684] worker_thread (kernel/workqueue.c:3342 (discriminator 2) kernel/workqueue.c:3429 (discriminator 2))
[   44.327292] kthread (kernel/kthread.c:388)
[   44.331342] ret_from_fork (arch/arm64/kernel/entry.S:861)

The problem is because bpf_arch_text_copy() silently fails to write to the
read-only area as a result of patch_map() faulting and the resulting
-EFAULT being chucked away.

Update patch_map() to use CONFIG_EXECMEM instead of
CONFIG_STRICT_MODULE_RWX to check for vmalloc addresses.

Link: https://lkml.kernel.org/r/20240521213813.703309-1-rppt@kernel.org
Fixes: 2c9e5d4 ("bpf: remove CONFIG_BPF_JIT dependency on CONFIG_MODULES of")
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reported-by: Klara Modin <klarasmodin@gmail.com>
Closes: https://lore.kernel.org/all/7983fbbf-0127-457c-9394-8d6e4299c685@gmail.com
Tested-by: Klara Modin <klarasmodin@gmail.com>
Cc: Björn Töpel <bjorn@kernel.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
ojeda pushed a commit that referenced this issue Jul 8, 2024
Currently, the ionic_run_xdp() doesn't handle multi-buffer packets
properly for XDP_TX and XDP_REDIRECT.
When a jumbo frame is received, the ionic_run_xdp() first makes xdp
frame with all necessary pages in the rx descriptor.
And if the action is either XDP_TX or XDP_REDIRECT, it should unmap
dma-mapping and reset page pointer to NULL for all pages, not only the
first page.
But it doesn't for SG pages. So, SG pages unexpectedly will be reused.
It eventually causes kernel panic.

Oops: general protection fault, probably for non-canonical address 0x504f4e4dbebc64ff: 0000 [#1] PREEMPT SMP NOPTI
CPU: 3 PID: 0 Comm: swapper/3 Not tainted 6.10.0-rc3+ #25
RIP: 0010:xdp_return_frame+0x42/0x90
Code: 01 75 12 5b 4c 89 e6 5d 31 c9 41 5c 31 d2 41 5d e9 73 fd ff ff 44 8b 6b 20 0f b7 43 0a 49 81 ed 68 01 00 00 49 29 c5 49 01 fd <41> 80 7d0
RSP: 0018:ffff99d00122ce08 EFLAGS: 00010202
RAX: 0000000000005453 RBX: ffff8d325f904000 RCX: 0000000000000001
RDX: 00000000670e1000 RSI: 000000011f90d000 RDI: 504f4e4d4c4b4a49
RBP: ffff99d003907740 R08: 0000000000000000 R09: 0000000000000000
R10: 000000011f90d000 R11: 0000000000000000 R12: ffff8d325f904010
R13: 504f4e4dbebc64fd R14: ffff8d3242b070c8 R15: ffff99d0039077c0
FS:  0000000000000000(0000) GS:ffff8d399f780000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f41f6c85e38 CR3: 000000037ac30000 CR4: 00000000007506f0
PKRU: 55555554
Call Trace:
 <IRQ>
 ? die_addr+0x33/0x90
 ? exc_general_protection+0x251/0x2f0
 ? asm_exc_general_protection+0x22/0x30
 ? xdp_return_frame+0x42/0x90
 ionic_tx_clean+0x211/0x280 [ionic 15881354510e6a9c655c59c54812b319ed2cd015]
 ionic_tx_cq_service+0xd3/0x210 [ionic 15881354510e6a9c655c59c54812b319ed2cd015]
 ionic_txrx_napi+0x41/0x1b0 [ionic 15881354510e6a9c655c59c54812b319ed2cd015]
 __napi_poll.constprop.0+0x29/0x1b0
 net_rx_action+0x2c4/0x350
 handle_softirqs+0xf4/0x320
 irq_exit_rcu+0x78/0xa0
 common_interrupt+0x77/0x90

Fixes: 5377805 ("ionic: implement xdp frags support")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ojeda pushed a commit that referenced this issue Oct 7, 2024
A dentry leak may be caused when a lookup cookie and a cull are concurrent:

            P1             |             P2
-----------------------------------------------------------
cachefiles_lookup_cookie
  cachefiles_look_up_object
    lookup_one_positive_unlocked
     // get dentry
                            cachefiles_cull
                              inode->i_flags |= S_KERNEL_FILE;
    cachefiles_open_file
      cachefiles_mark_inode_in_use
        __cachefiles_mark_inode_in_use
          can_use = false
          if (!(inode->i_flags & S_KERNEL_FILE))
            can_use = true
	  return false
        return false
        // Returns an error but doesn't put dentry

After that the following WARNING will be triggered when the backend folder
is umounted:

==================================================================
BUG: Dentry 000000008ad87947{i=7a,n=Dx_1_1.img}  still in use (1) [unmount of ext4 sda]
WARNING: CPU: 4 PID: 359261 at fs/dcache.c:1767 umount_check+0x5d/0x70
CPU: 4 PID: 359261 Comm: umount Not tainted 6.6.0-dirty #25
RIP: 0010:umount_check+0x5d/0x70
Call Trace:
 <TASK>
 d_walk+0xda/0x2b0
 do_one_tree+0x20/0x40
 shrink_dcache_for_umount+0x2c/0x90
 generic_shutdown_super+0x20/0x160
 kill_block_super+0x1a/0x40
 ext4_kill_sb+0x22/0x40
 deactivate_locked_super+0x35/0x80
 cleanup_mnt+0x104/0x160
==================================================================

Whether cachefiles_open_file() returns true or false, the reference count
obtained by lookup_positive_unlocked() in cachefiles_look_up_object()
should be released.

Therefore release that reference count in cachefiles_look_up_object() to
fix the above issue and simplify the code.

Fixes: 1f08c92 ("cachefiles: Implement backing file wrangling")
Cc: stable@kernel.org
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240829083409.3788142-1-libaokun@huaweicloud.com
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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