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  1. 13 Aug, 2018 18 commits
  3. 12 Aug, 2018 4 commits
    • Linus Torvalds's avatar
      Linux 4.18 · 94710cac
      Linus Torvalds authored
      94710cac
    • Linus Torvalds's avatar
      Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi · 921195d3
      Linus Torvalds authored 
      Pull SCSI fixes from James Bottomley:
 "Eight fixes.

  The most important one is the mpt3sas fix which makes the driver work
  again on big endian systems. The rest are mostly minor error path or
  checker issues and the vmw_scsi one fixes a performance problem"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: vmw_pvscsi: Return DID_RESET for status SAM_STAT_COMMAND_TERMINATED
  scsi: sr: Avoid that opening a CD-ROM hangs with runtime power management enabled
  scsi: mpt3sas: Swap I/O memory read value back to cpu endianness
  scsi: fcoe: clear FC_RP_STARTED flags when receiving a LOGO
  scsi: fcoe: drop frames in ELS LOGO error path
  scsi: fcoe: fix use-after-free in fcoe_ctlr_els_send
  scsi: qedi: Fix a potential buffer overflow
  scsi: qla2xxx: Fix memory leak for allocating abort IOCB
      921195d3
    • Linus Torvalds's avatar
      init: rename and re-order boot_cpu_state_init() · b5b1404d
      Linus Torvalds authored 
      This is purely a preparatory patch for upcoming changes during the 4.19
merge window.

We have a function called "boot_cpu_state_init()" that isn't really
about the bootup cpu state: that is done much earlier by the similarly
named "boot_cpu_init()" (note lack of "state" in name).

This function initializes some hotplug CPU state, and needs to run after
the percpu data has been properly initialized.  It even has a comment to
that effect.

Except it _doesn't_ actually run after the percpu data has been properly
initialized.  On x86 it happens to do that, but on at least arm and
arm64, the percpu base pointers are initialized by the arch-specific
'smp_prepare_boot_cpu()' hook, which ran _after_ boot_cpu_state_init().

This had some unexpected results, and in particular we have a patch
pending for the merge window that did the obvious cleanup of using
'this_cpu_write()' in the cpu hotplug init code:

  -       per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE;
  +       this_cpu_write(cpuhp_state.state, CPUHP_ONLINE);

which is obviously the right thing to do.  Except because of the
ordering issue, it actually failed miserably and unexpectedly on arm64.

So this just fixes the ordering, and changes the name of the function to
be 'boot_cpu_hotplug_init()' to make it obvious that it's about cpu
hotplug state, because the core CPU state was supposed to have already
been done earlier.

Marked for stable, since the (not yet merged) patch that will show this
problem is marked for stable.
Reported-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reported-by: default avatarMian Yousaf Kaukab <yousaf.kaukab@suse.com>
Suggested-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: stable@kernel.org
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b5b1404d
    • Linus Torvalds's avatar
      Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs · d6dd6431
      Linus Torvalds authored 
      Pull vfs fixes from Al Viro:
 "A bunch of race fixes, mostly around lazy pathwalk.

  All of it is -stable fodder, a large part going back to 2013"

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  make sure that __dentry_kill() always invalidates d_seq, unhashed or not
  fix __legitimize_mnt()/mntput() race
  fix mntput/mntput race
  root dentries need RCU-delayed freeing
      d6dd6431
  5. 11 Aug, 2018 9 commits
  7. 10 Aug, 2018 2 commits
  9. 09 Aug, 2018 7 commits
    • Al Viro's avatar
      make sure that __dentry_kill() always invalidates d_seq, unhashed or not · 4c0d7cd5
      Al Viro authored 
      RCU pathwalk relies upon the assumption that anything that changes
->d_inode of a dentry will invalidate its ->d_seq.  That's almost
true - the one exception is that the final dput() of already unhashed
dentry does *not* touch ->d_seq at all.  Unhashing does, though,
so for anything we'd found by RCU dcache lookup we are fine.
Unfortunately, we can *start* with an unhashed dentry or jump into
it.

We could try and be careful in the (few) places where that could
happen.  Or we could just make the final dput() invalidate the damn
thing, unhashed or not.  The latter is much simpler and easier to
backport, so let's do it that way.
Reported-by: default avatar"Dae R. Jeong" <threeearcat@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      4c0d7cd5
    • Al Viro's avatar
      fix __legitimize_mnt()/mntput() race · 119e1ef8
      Al Viro authored 
      __legitimize_mnt() has two problems - one is that in case of success
the check of mount_lock is not ordered wrt preceding increment of
refcount, making it possible to have successful __legitimize_mnt()
on one CPU just before the otherwise final mntpu() on another,
with __legitimize_mnt() not seeing mntput() taking the lock and
mntput() not seeing the increment done by __legitimize_mnt().
Solved by a pair of barriers.

Another is that failure of __legitimize_mnt() on the second
read_seqretry() leaves us with reference that'll need to be
dropped by caller; however, if that races with final mntput()
we can end up with caller dropping rcu_read_lock() and doing
mntput() to release that reference - with the first mntput()
having freed the damn thing just as rcu_read_lock() had been
dropped.  Solution: in "do mntput() yourself" failure case
grab mount_lock, check if MNT_DOOMED has been set by racing
final mntput() that has missed our increment and if it has -
undo the increment and treat that as "failure, caller doesn't
need to drop anything" case.

It's not easy to hit - the final mntput() has to come right
after the first read_seqretry() in __legitimize_mnt() *and*
manage to miss the increment done by __legitimize_mnt() before
the second read_seqretry() in there.  The things that are almost
impossible to hit on bare hardware are not impossible on SMP
KVM, though...
Reported-by: default avatarOleg Nesterov <oleg@redhat.com>
Fixes: 48a066e7 ("RCU'd vsfmounts")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      119e1ef8
    • Al Viro's avatar
      fix mntput/mntput race · 9ea0a46c
      Al Viro authored 
      mntput_no_expire() does the calculation of total refcount under mount_lock;
unfortunately, the decrement (as well as all increments) are done outside
of it, leading to false positives in the "are we dropping the last reference"
test.  Consider the following situation:
	* mnt is a lazy-umounted mount, kept alive by two opened files.  One
of those files gets closed.  Total refcount of mnt is 2.  On CPU 42
mntput(mnt) (called from __fput()) drops one reference, decrementing component
	* After it has looked at component #0, the process on CPU 0 does
mntget(), incrementing component #0, gets preempted and gets to run again -
on CPU 69.  There it does mntput(), which drops the reference (component #69)
and proceeds to spin on mount_lock.
	* On CPU 42 our first mntput() finishes counting.  It observes the
decrement of component #69, but not the increment of component #0.  As the
result, the total it gets is not 1 as it should've been - it's 0.  At which
point we decide that vfsmount needs to be killed and proceed to free it and
shut the filesystem down.  However, there's still another opened file
on that filesystem, with reference to (now freed) vfsmount, etc. and we are
screwed.

It's not a wide race, but it can be reproduced with artificial slowdown of
the mnt_get_count() loop, and it should be easier to hit on SMP KVM setups.

Fix consists of moving the refcount decrement under mount_lock; the tricky
part is that we want (and can) keep the fast case (i.e. mount that still
has non-NULL ->mnt_ns) entirely out of mount_lock.  All places that zero
mnt->mnt_ns are dropping some reference to mnt and they call synchronize_rcu()
before that mntput().  IOW, if mntput() observes (under rcu_read_lock())
a non-NULL ->mnt_ns, it is guaranteed that there is another reference yet to
be dropped.
Reported-by: default avatarJann Horn <jannh@google.com>
Tested-by: default avatarJann Horn <jannh@google.com>
Fixes: 48a066e7 ("RCU'd vsfmounts")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      9ea0a46c
    • Daniel Borkmann's avatar
      Merge branch 'bpf-fix-cpu-and-devmap-teardown' · 9c954201
      Daniel Borkmann authored 
      Jesper Dangaard Brouer says:

====================
Removing entries from cpumap and devmap, goes through a number of
syncronization steps to make sure no new xdp_frames can be enqueued.
But there is a small chance, that xdp_frames remains which have not
been flushed/processed yet.  Flushing these during teardown, happens
from RCU context and not as usual under RX NAPI context.

The optimization introduced in commt 389ab7f0 ("xdp: introduce
xdp_return_frame_rx_napi"), missed that the flush operation can also
be called from RCU context.  Thus, we cannot always use the
xdp_return_frame_rx_napi call, which take advantage of the protection
provided by XDP RX running under NAPI protection.

The samples/bpf xdp_redirect_cpu have a --stress-mode, that is
adjusted to easier reproduce (verified by Red Hat QA).
====================
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      9c954201
    • Jesper Dangaard Brouer's avatar
      xdp: fix bug in devmap teardown code path · 1bf9116d
      Jesper Dangaard Brouer authored 
      Like cpumap teardown, the devmap teardown code also flush remaining
xdp_frames, via bq_xmit_all() in case map entry is removed.  The code
can call xdp_return_frame_rx_napi, from the the wrong context, in-case
ndo_xdp_xmit() fails.

Fixes: 389ab7f0 ("xdp: introduce xdp_return_frame_rx_napi")
Fixes: 735fc405 ("xdp: change ndo_xdp_xmit API to support bulking")
Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      1bf9116d
    • Jesper Dangaard Brouer's avatar
      samples/bpf: xdp_redirect_cpu adjustment to reproduce teardown race easier · 37d7ff25
      Jesper Dangaard Brouer authored 
      The teardown race in cpumap is really hard to reproduce.  These changes
makes it easier to reproduce, for QA.

The --stress-mode now have a case of a very small queue size of 8, that helps
to trigger teardown flush to encounter a full queue, which results in calling
xdp_return_frame API, in a non-NAPI protect context.

Also increase MAX_CPUS, as my QA department have larger machines than me.
Tested-by: default avatarJean-Tsung Hsiao <jhsiao@redhat.com>
Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      37d7ff25
    • Jesper Dangaard Brouer's avatar
      xdp: fix bug in cpumap teardown code path · ad0ab027
      Jesper Dangaard Brouer authored 
      When removing a cpumap entry, a number of syncronization steps happen.
Eventually the teardown code __cpu_map_entry_free is invoked from/via
call_rcu.

The teardown code __cpu_map_entry_free() flushes remaining xdp_frames,
by invoking bq_flush_to_queue, which calls xdp_return_frame_rx_napi().
The issues is that the teardown code is not running in the RX NAPI
code path.  Thus, it is not allowed to invoke the NAPI variant of
xdp_return_frame.

This bug was found and triggered by using the --stress-mode option to
the samples/bpf program xdp_redirect_cpu.  It is hard to trigger,
because the ptr_ring have to be full and cpumap bulk queue max
contains 8 packets, and a remote CPU is racing to empty the ptr_ring
queue.

Fixes: 389ab7f0 ("xdp: introduce xdp_return_frame_rx_napi")
Tested-by: default avatarJean-Tsung Hsiao <jhsiao@redhat.com>
Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      ad0ab027
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