In time-travel mode, cpu_relax() currently does actual CPU relax,
but that doesn't affect the simulation. Ideally, we wouldn't run
anything that uses it in simulation, but if we actually have virtio
devices combined with the same simulation it's possible. Implement
cpu_relax() as ndelay(1) in this case, using time_travel_ndelay(1)
directly to catch errors if this is used erroneously in builds that
don't set CONFIG_UML_TIME_TRAVEL_SUPPORT.

While at it, convert it to an __always_inline and also add that to
rep_nop() like the original does now.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

In external or inf-cpu time-travel mode, ndelay/udelay currently
just waste CPU time since the simulation time doesn't advance.
Implement them properly in this case.

Note that the "if (time_travel_mode == ...)" parts compile out
if CONFIG_UML_TIME_TRAVEL_SUPPORT isn't set, time_travel_mode is
defined to TT_MODE_OFF in that case.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

This implements synchronized time-travel mode which - using a special
application on a unix socket - lets multiple machines take part in a
time-travelling simulation together.

The protocol for the unix domain socket is defined in the new file
include/uapi/linux/um_timetravel.h.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

Implement in-band notifications that are necessary for running
vhost-user devices under externally synchronized time-travel
mode (which is in a follow-up patch). This feature makes what
usually should be eventfd notifications in-band messages.

We'll prefer this feature, under the assumption that only a
few (simulation) devices will ever support it, since it's not
very efficient.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

Instead of tracking all the various timer configurations,
modify the time-travel mode to have an event scheduler and
use a timer event on the scheduler to handle the different
timer configurations.

This doesn't change the function right now, but it prepares
the code for having different kinds of events in the future
(i.e. interrupts coming from other devices that are part of
co-simulation.)

While at it, also move time_travel_sleep() to time.c to
reduce the externally visible API surface.

Also, we really should mark time-travel as incompatible with
SMP, even if UML doesn't support SMP yet.

Finally, I noticed a bug while developing this - if we move
time forward due to consuming time while reading the clock,
we might move across the next event and that would cause us
to go backward in time when we then handle that event. Fix
that by invoking the whole event machine in this case, but
in order to simplify this, make reading the clock only cost
something when interrupts are not disabled. Otherwise, we'd
have to hook into the interrupt delivery machinery etc. and
that's somewhat intrusive.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

This file isn't really shared, it's only used on the kernel side,
not on the user side. Remove the include from the user-side and
move the file to a better place.

While at it, rename it to time-internal.h, it's not really just
timers but all kinds of things related to timekeeping.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

Improve readability and maintainability by replacing a hardcoded string
allocation and formatting by the use of the kasprintf() helper.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

When building UML with glibc 2.17 installed, compilation
of arch/um/os-Linux/file.c fails due to failure to find
FALLOC_FL_PUNCH_HOLE and FALLOC_FL_KEEP_SIZE definitions.

It appears that /usr/include/bits/fcntl-linux.h (indirectly
included by /usr/include/fcntl.h) does not include falloc.h
with an older glibc, whereas a more up-to-date version
does.

Adding the direct include to file.c resolves the issue
and does not cause problems for more recent glibc.

Fixes: 50109b5a ("um: Add support for DISCARD in the UBD Driver")
Cc: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

Should bulk_req_safe_read return an error, we want to retry the read,
otherwise, even though no IO will be done, os_write_file might still end
up writing garbage to the pipe.

Cc: Martyn Welch <martyn.welch@collabora.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

On the hypervisor side, when completing commands and the pipe is full,
we retry writing only the entries that failed, by offsetting
io_req_buffer, but we don't reduce the number of bytes written, which
can cause a buffer overrun of io_req_buffer, and write garbage to the
pipe.

Cc: Martyn Welch <martyn.welch@collabora.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

When statically linked, the .text section in UML kernels is not page
aligned, causing it to share a page with the executable headers. As
.text and the executable headers have different permissions, this causes
the kernel to wish to map the same page twice (once as headers with r--
permissions, once as .text with r-x permissions), causing a segfault,
and a nasty message printed to the host kernel's dmesg:

"Uhuuh, elf segment at 0000000060000000 requested but the memory is
mapped already"

By aligning the .text to a page boundary (as in the dynamically linked
version in dyn.lds.S), there is no such overlap, and the kernel runs
correctly.
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

The "#ifdef undef" construction effectively disabled the timer.
It causes to the fact that this timer did nothing, so delete it.
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

In-tree drivers don't need to manage internal version because
they are aligned to the global Linux kernel version, which is
reported by default with "ethtool -i".
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

sizeof gives us the size of the pointer variable, not of the
area it points to. So the number of bytes copied by umid_file_name()
is 8.
We should pass in the correct length of the file buffer.
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

console_drivers is kind of (semi-)private variable to the console code.
Direct use of it make us stuck with it being exported here and there.
Reduce use of console_drivers by replacing it with for_each_console().

Cc: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

CONFIG_IOSCHED_CFQ is gone since commit f382fb0b ("block: remove legacy
IO schedulers").

The IOSCHED_BFQ seems to replace IOSCHED_CFQ so select it in configs
previously choosing the latter.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

Pull btrfs fixes from David Sterba:
 "Two fixes.

  The first is a regression: when dropping some incompat bits the
  conditions were reversed. The other is a fix for rename whiteout
  potentially leaving stack memory linked to a list"

* tag 'for-5.6-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: fix removal of raid[56|1c34} incompat flags after removing block group
  btrfs: fix log context list corruption after rename whiteout error

Merge misc fixes from Andrew Morton:
 "10 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  x86/mm: split vmalloc_sync_all()
  mm, slub: prevent kmalloc_node crashes and memory leaks
  mm/mmu_notifier: silence PROVE_RCU_LIST warnings
  epoll: fix possible lost wakeup on epoll_ctl() path
  mm: do not allow MADV_PAGEOUT for CoW pages
  mm, memcg: throttle allocators based on ancestral memory.high
  mm, memcg: fix corruption on 64-bit divisor in memory.high throttling
  page-flags: fix a crash at SetPageError(THP_SWAP)
  mm/hotplug: fix hot remove failure in SPARSEMEM|!VMEMMAP case
  memcg: fix NULL pointer dereference in __mem_cgroup_usage_unregister_event

Commit 3f8fd02b ("mm/vmalloc: Sync unmappings in
__purge_vmap_area_lazy()") introduced a call to vmalloc_sync_all() in
the vunmap() code-path.  While this change was necessary to maintain
correctness on x86-32-pae kernels, it also adds additional cycles for
architectures that don't need it.

Specifically on x86-64 with CONFIG_VMAP_STACK=y some people reported
severe performance regressions in micro-benchmarks because it now also
calls the x86-64 implementation of vmalloc_sync_all() on vunmap().  But
the vmalloc_sync_all() implementation on x86-64 is only needed for newly
created mappings.

To avoid the unnecessary work on x86-64 and to gain the performance
back, split up vmalloc_sync_all() into two functions:

	* vmalloc_sync_mappings(), and
	* vmalloc_sync_unmappings()

Most call-sites to vmalloc_sync_all() only care about new mappings being
synchronized.  The only exception is the new call-site added in the
above mentioned commit.

Shile Zhang directed us to a report of an 80% regression in reaim
throughput.

Fixes: 3f8fd02b ("mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy()")
Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: Shile Zhang <shile.zhang@linux.alibaba.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Borislav Petkov <bp@suse.de>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>	[GHES]
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20191009124418.8286-1-joro@8bytes.org
Link: https://lists.01.org/hyperkitty/list/lkp@lists.01.org/thread/4D3JPPHBNOSPFK2KEPC6KGKS6J25AIDB/
Link: http://lkml.kernel.org/r/20191113095530.228959-1-shile.zhang@linux.alibaba.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Sachin reports [1] a crash in SLUB __slab_alloc():

  BUG: Kernel NULL pointer dereference on read at 0x000073b0
  Faulting instruction address: 0xc0000000003d55f4
  Oops: Kernel access of bad area, sig: 11 [#1]
  LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
  Modules linked in:
  CPU: 19 PID: 1 Comm: systemd Not tainted 5.6.0-rc2-next-20200218-autotest #1
  NIP:  c0000000003d55f4 LR: c0000000003d5b94 CTR: 0000000000000000
  REGS: c0000008b37836d0 TRAP: 0300   Not tainted  (5.6.0-rc2-next-20200218-autotest)
  MSR:  8000000000009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 24004844  XER: 00000000
  CFAR: c00000000000dec4 DAR: 00000000000073b0 DSISR: 40000000 IRQMASK: 1
  GPR00: c0000000003d5b94 c0000008b3783960 c00000000155d400 c0000008b301f500
  GPR04: 0000000000000dc0 0000000000000002 c0000000003443d8 c0000008bb398620
  GPR08: 00000008ba2f0000 0000000000000001 0000000000000000 0000000000000000
  GPR12: 0000000024004844 c00000001ec52a00 0000000000000000 0000000000000000
  GPR16: c0000008a1b20048 c000000001595898 c000000001750c18 0000000000000002
  GPR20: c000000001750c28 c000000001624470 0000000fffffffe0 5deadbeef0000122
  GPR24: 0000000000000001 0000000000000dc0 0000000000000002 c0000000003443d8
  GPR28: c0000008b301f500 c0000008bb398620 0000000000000000 c00c000002287180
  NIP ___slab_alloc+0x1f4/0x760
  LR __slab_alloc+0x34/0x60
  Call Trace:
    ___slab_alloc+0x334/0x760 (unreliable)
    __slab_alloc+0x34/0x60
    __kmalloc_node+0x110/0x490
    kvmalloc_node+0x58/0x110
    mem_cgroup_css_online+0x108/0x270
    online_css+0x48/0xd0
    cgroup_apply_control_enable+0x2ec/0x4d0
    cgroup_mkdir+0x228/0x5f0
    kernfs_iop_mkdir+0x90/0xf0
    vfs_mkdir+0x110/0x230
    do_mkdirat+0xb0/0x1a0
    system_call+0x5c/0x68

This is a PowerPC platform with following NUMA topology:

  available: 2 nodes (0-1)
  node 0 cpus:
  node 0 size: 0 MB
  node 0 free: 0 MB
  node 1 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
  node 1 size: 35247 MB
  node 1 free: 30907 MB
  node distances:
  node   0   1
    0:  10  40
    1:  40  10

  possible numa nodes: 0-31

This only happens with a mmotm patch "mm/memcontrol.c: allocate
shrinker_map on appropriate NUMA node" [2] which effectively calls
kmalloc_node for each possible node.  SLUB however only allocates
kmem_cache_node on online N_NORMAL_MEMORY nodes, and relies on
node_to_mem_node to return such valid node for other nodes since commit
a561ce00 ("slub: fall back to node_to_mem_node() node if allocating
on memoryless node").  This is however not true in this configuration
where the _node_numa_mem_ array is not initialized for nodes 0 and 2-31,
thus it contains zeroes and get_partial() ends up accessing
non-allocated kmem_cache_node.

A related issue was reported by Bharata (originally by Ramachandran) [3]
where a similar PowerPC configuration, but with mainline kernel without
patch [2] ends up allocating large amounts of pages by kmalloc-1k
kmalloc-512.  This seems to have the same underlying issue with
node_to_mem_node() not behaving as expected, and might probably also
lead to an infinite loop with CONFIG_SLUB_CPU_PARTIAL [4].

This patch should fix both issues by not relying on node_to_mem_node()
anymore and instead simply falling back to NUMA_NO_NODE, when
kmalloc_node(node) is attempted for a node that's not online, or has no
usable memory.  The "usable memory" condition is also changed from
node_present_pages() to N_NORMAL_MEMORY node state, as that is exactly
the condition that SLUB uses to allocate kmem_cache_node structures.
The check in get_partial() is removed completely, as the checks in
___slab_alloc() are now sufficient to prevent get_partial() being
reached with an invalid node.

[1] https://lore.kernel.org/linux-next/3381CD91-AB3D-4773-BA04-E7A072A63968@linux.vnet.ibm.com/
[2] https://lore.kernel.org/linux-mm/fff0e636-4c36-ed10-281c-8cdb0687c839@virtuozzo.com/
[3] https://lore.kernel.org/linux-mm/20200317092624.GB22538@in.ibm.com/
[4] https://lore.kernel.org/linux-mm/088b5996-faae-8a56-ef9c-5b567125ae54@suse.cz/

Fixes: a561ce00 ("slub: fall back to node_to_mem_node() node if allocating on memoryless node")
Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Reported-by: PUVICHAKRAVARTHY RAMACHANDRAN <puvichakravarthy@in.ibm.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Tested-by: Bharata B Rao <bharata@linux.ibm.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Christopher Lameter <cl@linux.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200320115533.9604-1-vbabka@suse.czDebugged-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

It is safe to traverse mm->notifier_subscriptions->list either under
SRCU read lock or mm->notifier_subscriptions->lock using
hlist_for_each_entry_rcu().  Silence the PROVE_RCU_LIST false positives,
for example,

  WARNING: suspicious RCU usage
  -----------------------------
  mm/mmu_notifier.c:484 RCU-list traversed in non-reader section!!

  other info that might help us debug this:

  rcu_scheduler_active = 2, debug_locks = 1
  3 locks held by libvirtd/802:
   #0: ffff9321e3f58148 (&mm->mmap_sem#2){++++}, at: do_mprotect_pkey+0xe1/0x3e0
   #1: ffffffff91ae6160 (mmu_notifier_invalidate_range_start){+.+.}, at: change_p4d_range+0x5fa/0x800
   #2: ffffffff91ae6e08 (srcu){....}, at: __mmu_notifier_invalidate_range_start+0x178/0x460

  stack backtrace:
  CPU: 7 PID: 802 Comm: libvirtd Tainted: G          I       5.6.0-rc6-next-20200317+ #2
  Hardware name: HP ProLiant BL460c Gen8, BIOS I31 11/02/2014
  Call Trace:
    dump_stack+0xa4/0xfe
    lockdep_rcu_suspicious+0xeb/0xf5
    __mmu_notifier_invalidate_range_start+0x3ff/0x460
    change_p4d_range+0x746/0x800
    change_protection+0x1df/0x300
    mprotect_fixup+0x245/0x3e0
    do_mprotect_pkey+0x23b/0x3e0
    __x64_sys_mprotect+0x51/0x70
    do_syscall_64+0x91/0xae8
    entry_SYSCALL_64_after_hwframe+0x49/0xb3
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Link: http://lkml.kernel.org/r/20200317175640.2047-1-cai@lca.pwSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This fixes possible lost wakeup introduced by commit a218cc49.
Originally modifications to ep->wq were serialized by ep->wq.lock, but
in commit a218cc49 ("epoll: use rwlock in order to reduce
ep_poll_callback() contention") a new rw lock was introduced in order to
relax fd event path, i.e. callers of ep_poll_callback() function.

After the change ep_modify and ep_insert (both are called on epoll_ctl()
path) were switched to ep->lock, but ep_poll (epoll_wait) was using
ep->wq.lock on wqueue list modification.

The bug doesn't lead to any wqueue list corruptions, because wake up
path and list modifications were serialized by ep->wq.lock internally,
but actual waitqueue_active() check prior wake_up() call can be
reordered with modifications of ep ready list, thus wake up can be lost.

And yes, can be healed by explicit smp_mb():

  list_add_tail(&epi->rdlink, &ep->rdllist);
  smp_mb();
  if (waitqueue_active(&ep->wq))
	wake_up(&ep->wp);

But let's make it simple, thus current patch replaces ep->wq.lock with
the ep->lock for wqueue modifications, thus wake up path always observes
activeness of the wqueue correcty.

Fixes: a218cc49 ("epoll: use rwlock in order to reduce ep_poll_callback() contention")
Reported-by: Max Neunhoeffer <max@arangodb.com>
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Max Neunhoeffer <max@arangodb.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Christopher Kohlhoff <chris.kohlhoff@clearpool.io>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jes Sorensen <jes.sorensen@gmail.com>
Cc: <stable@vger.kernel.org>	[5.1+]
Link: http://lkml.kernel.org/r/20200214170211.561524-1-rpenyaev@suse.de
References: https://bugzilla.kernel.org/show_bug.cgi?id=205933Bisected-by: Max Neunhoeffer <max@arangodb.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Jann has brought up a very interesting point [1].  While shared pages
are excluded from MADV_PAGEOUT normally, CoW pages can be easily
reclaimed that way.  This can lead to all sorts of hard to debug
problems.  E.g.  performance problems outlined by Daniel [2].

There are runtime environments where there is a substantial memory
shared among security domains via CoW memory and a easy to reclaim way
of that memory, which MADV_{COLD,PAGEOUT} offers, can lead to either
performance degradation in for the parent process which might be more
privileged or even open side channel attacks.

The feasibility of the latter is not really clear to me TBH but there is
no real reason for exposure at this stage.  It seems there is no real
use case to depend on reclaiming CoW memory via madvise at this stage so
it is much easier to simply disallow it and this is what this patch
does.  Put it simply MADV_{PAGEOUT,COLD} can operate only on the
exclusively owned memory which is a straightforward semantic.

[1] http://lkml.kernel.org/r/CAG48ez0G3JkMq61gUmyQAaCq=_TwHbi1XKzWRooxZkv08PQKuw@mail.gmail.com
[2] http://lkml.kernel.org/r/CAKOZueua_v8jHCpmEtTB6f3i9e2YnmX4mqdYVWhV4E=Z-n+zRQ@mail.gmail.com

Fixes: 9c276cc6 ("mm: introduce MADV_COLD")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Daniel Colascione <dancol@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200312082248.GS23944@dhcp22.suse.czSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Prior to this commit, we only directly check the affected cgroup's
memory.high against its usage.  However, it's possible that we are being
reclaimed as a result of hitting an ancestor memory.high and should be
penalised based on that, instead.

This patch changes memory.high overage throttling to use the largest
overage in its ancestors when considering how many penalty jiffies to
charge.  This makes sure that we penalise poorly behaving cgroups in the
same way regardless of at what level of the hierarchy memory.high was
breached.

Fixes: 0e4b01df ("mm, memcg: throttle allocators when failing reclaim over memory.high")
Reported-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>	[5.4.x+]
Link: http://lkml.kernel.org/r/8cd132f84bd7e16cdb8fde3378cdbf05ba00d387.1584036142.git.chris@chrisdown.nameSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 0e4b01df had a bunch of fixups to use the right division
method.  However, it seems that after all that it still wasn't right --
div_u64 takes a 32-bit divisor.

The headroom is still large (2^32 pages), so on mundane systems you
won't hit this, but this should definitely be fixed.

Fixes: 0e4b01df ("mm, memcg: throttle allocators when failing reclaim over memory.high")
Reported-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: <stable@vger.kernel.org>	[5.4.x+]
Link: http://lkml.kernel.org/r/80780887060514967d414b3cd91f9a316a16ab98.1584036142.git.chris@chrisdown.nameSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit bd4c82c2 ("mm, THP, swap: delay splitting THP after swapped
out") supported writing THP to a swap device but forgot to upgrade an
older commit df8c94d1 ("page-flags: define behavior of FS/IO-related
flags on compound pages") which could trigger a crash during THP
swapping out with DEBUG_VM_PGFLAGS=y,

  kernel BUG at include/linux/page-flags.h:317!

  page dumped because: VM_BUG_ON_PAGE(1 && PageCompound(page))
  page:fffff3b2ec3a8000 refcount:512 mapcount:0 mapping:000000009eb0338c index:0x7f6e58200 head:fffff3b2ec3a8000 order:9 compound_mapcount:0 compound_pincount:0
  anon flags: 0x45fffe0000d8454(uptodate|lru|workingset|owner_priv_1|writeback|head|reclaim|swapbacked)

  end_swap_bio_write()
    SetPageError(page)
      VM_BUG_ON_PAGE(1 && PageCompound(page))

  <IRQ>
  bio_endio+0x297/0x560
  dec_pending+0x218/0x430 [dm_mod]
  clone_endio+0xe4/0x2c0 [dm_mod]
  bio_endio+0x297/0x560
  blk_update_request+0x201/0x920
  scsi_end_request+0x6b/0x4b0
  scsi_io_completion+0x509/0x7e0
  scsi_finish_command+0x1ed/0x2a0
  scsi_softirq_done+0x1c9/0x1d0
  __blk_mqnterrupt+0xf/0x20
  </IRQ>

Fix by checking PF_NO_TAIL in those places instead.

Fixes: bd4c82c2 ("mm, THP, swap: delay splitting THP after swapped out")
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200310235846.1319-1-cai@lca.pwSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In section_deactivate(), pfn_to_page() doesn't work any more after
ms->section_mem_map is resetting to NULL in SPARSEMEM|!VMEMMAP case.  It
causes a hot remove failure:

  kernel BUG at mm/page_alloc.c:4806!
  invalid opcode: 0000 [#1] SMP PTI
  CPU: 3 PID: 8 Comm: kworker/u16:0 Tainted: G        W         5.5.0-next-20200205+ #340
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
  Workqueue: kacpi_hotplug acpi_hotplug_work_fn
  RIP: 0010:free_pages+0x85/0xa0
  Call Trace:
   __remove_pages+0x99/0xc0
   arch_remove_memory+0x23/0x4d
   try_remove_memory+0xc8/0x130
   __remove_memory+0xa/0x11
   acpi_memory_device_remove+0x72/0x100
   acpi_bus_trim+0x55/0x90
   acpi_device_hotplug+0x2eb/0x3d0
   acpi_hotplug_work_fn+0x1a/0x30
   process_one_work+0x1a7/0x370
   worker_thread+0x30/0x380
   kthread+0x112/0x130
   ret_from_fork+0x35/0x40

Let's move the ->section_mem_map resetting after
depopulate_section_memmap() to fix it.

[akpm@linux-foundation.org: remove unneeded initialization, per David]
Fixes: ba72b4c8 ("mm/sparsemem: support sub-section hotplug")
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200307084229.28251-2-bhe@redhat.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

An eventfd monitors multiple memory thresholds of the cgroup, closes them,
the kernel deletes all events related to this eventfd.  Before all events
are deleted, another eventfd monitors the memory threshold of this cgroup,
leading to a crash:

  BUG: kernel NULL pointer dereference, address: 0000000000000004
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 800000033058e067 P4D 800000033058e067 PUD 3355ce067 PMD 0
  Oops: 0002 [#1] SMP PTI
  CPU: 2 PID: 14012 Comm: kworker/2:6 Kdump: loaded Not tainted 5.6.0-rc4 #3
  Hardware name: LENOVO 20AWS01K00/20AWS01K00, BIOS GLET70WW (2.24 ) 05/21/2014
  Workqueue: events memcg_event_remove
  RIP: 0010:__mem_cgroup_usage_unregister_event+0xb3/0x190
  RSP: 0018:ffffb47e01c4fe18 EFLAGS: 00010202
  RAX: 0000000000000001 RBX: ffff8bb223a8a000 RCX: 0000000000000001
  RDX: 0000000000000001 RSI: ffff8bb22fb83540 RDI: 0000000000000001
  RBP: ffffb47e01c4fe48 R08: 0000000000000000 R09: 0000000000000010
  R10: 000000000000000c R11: 071c71c71c71c71c R12: ffff8bb226aba880
  R13: ffff8bb223a8a480 R14: 0000000000000000 R15: 0000000000000000
  FS:  0000000000000000(0000) GS:ffff8bb242680000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000004 CR3: 000000032c29c003 CR4: 00000000001606e0
  Call Trace:
    memcg_event_remove+0x32/0x90
    process_one_work+0x172/0x380
    worker_thread+0x49/0x3f0
    kthread+0xf8/0x130
    ret_from_fork+0x35/0x40
  CR2: 0000000000000004

We can reproduce this problem in the following ways:

1. We create a new cgroup subdirectory and a new eventfd, and then we
   monitor multiple memory thresholds of the cgroup through this eventfd.

2.  closing this eventfd, and __mem_cgroup_usage_unregister_event ()
   will be called multiple times to delete all events related to this
   eventfd.

The first time __mem_cgroup_usage_unregister_event() is called, the
kernel will clear all items related to this eventfd in thresholds->
primary.

Since there is currently only one eventfd, thresholds-> primary becomes
empty, so the kernel will set thresholds-> primary and hresholds-> spare
to NULL.  If at this time, the user creates a new eventfd and monitor
the memory threshold of this cgroup, kernel will re-initialize
thresholds-> primary.

Then when __mem_cgroup_usage_unregister_event () is called for the
second time, because thresholds-> primary is not empty, the system will
access thresholds-> spare, but thresholds-> spare is NULL, which will
trigger a crash.

In general, the longer it takes to delete all events related to this
eventfd, the easier it is to trigger this problem.

The solution is to check whether the thresholds associated with the
eventfd has been cleared when deleting the event.  If so, we do nothing.

[akpm@linux-foundation.org: fix comment, per Kirill]
Fixes: 907860ed ("cgroups: make cftype.unregister_event() void-returning")
Signed-off-by: Chunguang Xu <brookxu@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/077a6f67-aefa-4591-efec-f2f3af2b0b02@gmail.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull block fixes from Jens Axboe:
 "Just two NVMe fabrics fixes that should go into 5.6"

* tag 'block-5.6-20200320' of git://git.kernel.dk/linux-block:
  nvmet-tcp: set MSG_MORE only if we actually have more to send
  nvme-rdma: Avoid double freeing of async event data

Pull io_uring fixes from Jens Axboe:
 "Two different fixes in here:

   - Fix for a potential NULL pointer deref for links with async or
     drain marked (Pavel)

   - Fix for not properly checking RLIMIT_NOFILE for async punted
     operations.

     This affects openat/openat2, which were added this cycle, and
     accept4. I did a full audit of other cases where we might check
     current->signal->rlim[] and found only RLIMIT_FSIZE for buffered
     writes and fallocate. That one is fixed and queued for 5.7 and
     marked stable"

* tag 'io_uring-5.6-20200320' of git://git.kernel.dk/linux-block:
  io_uring: make sure accept honor rlimit nofile
  io_uring: make sure openat/openat2 honor rlimit nofile
  io_uring: NULL-deref for IOSQE_{ASYNC,DRAIN}

Pull turbostat updates from Len Brown:
 "Update to turbostat v20.03.20.

  These patches unlock the full turbostat features for some new
  machines, plus a couple other minor tweaks"

* 'turbostat' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux:
  tools/power turbostat: update version
  tools/power turbostat: Print cpuidle information
  tools/power turbostat: Fix 32-bit capabilities warning
  tools/power turbostat: Fix missing SYS_LPI counter on some Chromebooks
  tools/power turbostat: Support Elkhart Lake
  tools/power turbostat: Support Jasper Lake
  tools/power turbostat: Support Ice Lake server
  tools/power turbostat: Support Tiger Lake
  tools/power turbostat: Fix gcc build warnings
  tools/power turbostat: Support Cometlake

Pull powerpc fixes from Michael Ellerman:
 "Two fixes for bugs introduced this cycle:

   - fix a crash when shutting down a KVM PR guest (our original style
     of KVM which doesn't use hypervisor mode)

   - fix for the recently added 32-bit KASAN_VMALLOC support

  Thanks to: Christophe Leroy, Greg Kurz, Sean Christopherson"

* tag 'powerpc-5.6-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  KVM: PPC: Fix kernel crash with PR KVM
  powerpc/kasan: Fix shadow memory protection with CONFIG_KASAN_VMALLOC

A stitch in time saves nine.
Signed-off-by: Len Brown <len.brown@intel.com>

Print cpuidle driver and governor.
Originally-by: Antti Laakso <antti.laakso@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

Pull NVMe fixes from Keith:

"Two late nvme fabrics fixes for 5.6: a double free with the rdma
 transport, and a regression fix for tcp; please pull."

* 'nvme-5.6-rc6' of git://git.infradead.org/nvme:
  nvmet-tcp: set MSG_MORE only if we actually have more to send
  nvme-rdma: Avoid double freeing of async event data

We are incorrectly dropping the raid56 and raid1c34 incompat flags when
there are still raid56 and raid1c34 block groups, not when we do not any
of those anymore. The logic just got unintentionally broken after adding
the support for the raid1c34 modes.

Fix this by clear the flags only if we do not have block groups with the
respective profiles.

Fixes: 9c907446 ("btrfs: drop incompat bit for raid1c34 after last block group is gone")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

When we send PDU data, we want to optimize the tcp stack
operation if we have more data to send. So when we set MSG_MORE
when:
- We have more fragments coming in the batch, or
- We have a more data to send in this PDU
- We don't have a data digest trailer
- We optimize with the SUCCESS flag and omit the NVMe completion
  (used if sq_head pointer update is disabled)

This addresses a regression in QD=1 with SUCCESS flag optimization
as we unconditionally set MSG_MORE when we didn't actually have
more data to send.

Fixes: 70583295 ("nvmet-tcp: implement C2HData SUCCESS optimization")
Reported-by: Mark Wunderlich <mark.wunderlich@intel.com>
Tested-by: Mark Wunderlich <mark.wunderlich@intel.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>

Pull arm64 fixes from Will Deacon:

 - Fix panic() when it occurs during secondary CPU startup

 - Fix "kpti=off" when KASLR is enabled

 - Fix howler in compat syscall table for vDSO clock_getres() fallback

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: compat: Fix syscall number of compat_clock_getres
  arm64: kpti: Fix "kpti=off" when KASLR is enabled
  arm64: smp: fix crash_smp_send_stop() behaviour
  arm64: smp: fix smp_send_stop() behaviour

Pull char/misc driver fixes from Greg KH:
 "Here are some small different driver fixes for 5.6-rc7:

   - binderfs fix, yet again

   - slimbus new device id added

   - hwtracing bugfixes for reported issues and a new device id

  All of these have been in linux-next with no reported issues"

* tag 'char-misc-5.6-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  intel_th: pci: Add Elkhart Lake CPU support
  intel_th: Fix user-visible error codes
  intel_th: msu: Fix the unexpected state warning
  stm class: sys-t: Fix the use of time_after()
  slimbus: ngd: add v2.1.0 compatible
  binderfs: use refcount for binder control devices too