Make sure the event_mutex is properly held during dyn_event_add call.
This is required when adding dynamic events.

Link: https://lkml.kernel.org/r/20220328223225.1992-1-beaub@linux.microsoft.com



Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

With the advent of various new memory types, some machines will have
multiple types of memory, e.g.  DRAM and PMEM (persistent memory).  The
memory subsystem of these machines can be called memory tiering system,
because the performance of the different types of memory are usually
different.

In such system, because of the memory accessing pattern changing etc,
some pages in the slow memory may become hot globally.  So in this
patch, the NUMA balancing mechanism is enhanced to optimize the page
placement among the different memory types according to hot/cold
dynamically.

In a typical memory tiering system, there are CPUs, fast memory and slow
memory in each physical NUMA node.  The CPUs and the fast memory will be
put in one logical node (called fast memory node), while the slow memory
will be put in another (faked) logical node (called slow memory node).
That is, the fast memory is regarded as local while the slow memory is
regarded as remote.  So it's possible for the recently accessed pages in
the slow memory node to be promoted to the fast memory node via the
existing NUMA balancing mechanism.

The original NUMA balancing mechanism will stop to migrate pages if the
free memory of the target node becomes below the high watermark.  This
is a reasonable policy if there's only one memory type.  But this makes
the original NUMA balancing mechanism almost do not work to optimize
page placement among different memory types.  Details are as follows.

It's the common cases that the working-set size of the workload is
larger than the size of the fast memory nodes.  Otherwise, it's
unnecessary to use the slow memory at all.  So, there are almost always
no enough free pages in the fast memory nodes, so that the globally hot
pages in the slow memory node cannot be promoted to the fast memory
node.  To solve the issue, we have 2 choices as follows,

a. Ignore the free pages watermark checking when promoting hot pages
   from the slow memory node to the fast memory node.  This will
   create some memory pressure in the fast memory node, thus trigger
   the memory reclaiming.  So that, the cold pages in the fast memory
   node will be demoted to the slow memory node.

b. Define a new watermark called wmark_promo which is higher than
   wmark_high, and have kswapd reclaiming pages until free pages reach
   such watermark.  The scenario is as follows: when we want to promote
   hot-pages from a slow memory to a fast memory, but fast memory's free
   pages would go lower than high watermark with such promotion, we wake
   up kswapd with wmark_promo watermark in order to demote cold pages and
   free us up some space.  So, next time we want to promote hot-pages we
   might have a chance of doing so.

The choice "a" may create high memory pressure in the fast memory node.
If the memory pressure of the workload is high, the memory pressure
may become so high that the memory allocation latency of the workload
is influenced, e.g.  the direct reclaiming may be triggered.

The choice "b" works much better at this aspect.  If the memory
pressure of the workload is high, the hot pages promotion will stop
earlier because its allocation watermark is higher than that of the
normal memory allocation.  So in this patch, choice "b" is implemented.
A new zone watermark (WMARK_PROMO) is added.  Which is larger than the
high watermark and can be controlled via watermark_scale_factor.

In addition to the original page placement optimization among sockets,
the NUMA balancing mechanism is extended to be used to optimize page
placement according to hot/cold among different memory types.  So the
sysctl user space interface (numa_balancing) is extended in a backward
compatible way as follow, so that the users can enable/disable these
functionality individually.

The sysctl is converted from a Boolean value to a bits field.  The
definition of the flags is,

- 0: NUMA_BALANCING_DISABLED
- 1: NUMA_BALANCING_NORMAL
- 2: NUMA_BALANCING_MEMORY_TIERING

We have tested the patch with the pmbench memory accessing benchmark
with the 80:20 read/write ratio and the Gauss access address
distribution on a 2 socket Intel server with Optane DC Persistent
Memory Model.  The test results shows that the pmbench score can
improve up to 95.9%.

Thanks Andrew Morton to help fix the document format error.

Link: https://lkml.kernel.org/r/20220221084529.1052339-3-ying.huang@intel.com


Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: zhongjiang-ali <zhongjiang-ali@linux.alibaba.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Feng Tang <feng.tang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "mm: enforce pageblock_order < MAX_ORDER".

Having pageblock_order >= MAX_ORDER seems to be able to happen in corner
cases and some parts of the kernel are not prepared for it.

For example, Aneesh has shown [1] that such kernels can be compiled on
ppc64 with 64k base pages by setting FORCE_MAX_ZONEORDER=8, which will
run into a WARN_ON_ONCE(order >= MAX_ORDER) in comapction code right
during boot.

We can get pageblock_order >= MAX_ORDER when the default hugetlb size is
bigger than the maximum allocation granularity of the buddy, in which
case we are no longer talking about huge pages but instead gigantic
pages.

Having pageblock_order >= MAX_ORDER can only make alloc_contig_range()
of such gigantic pages more likely to succeed.

Reliable use of gigantic pages either requires boot time allcoation or
CMA, no need to overcomplicate some places in the kernel to optimize for
corner cases that are broken in other areas of the kernel.

This patch (of 2):

Let's enforce pageblock_order < MAX_ORDER and simplify.

Especially patch #1 can be regarded a cleanup before:
	[PATCH v5 0/6] Use pageblock_order for cma and alloc_contig_range
	alignment. [2]

[1] https://lkml.kernel.org/r/87r189a2ks.fsf@linux.ibm.com
[2] https://lkml.kernel.org/r/20220211164135.1803616-1-zi.yan@sent.com

Link: https://lkml.kernel.org/r/20220214174132.219303-2-david@redhat.com


Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: Rob Herring <robh@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: John Garry via iommu <iommu@lists.linux-foundation.org>

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Qian Cai reported a boot crash on arm64 systems, caused by:

  0fb3978b ("sched/numa: Fix NUMA topology for systems with CPU-less nodes")

The bug is that node_state() must be supplied a valid node_states[] array index,
but in task_numa_placement() the max_nid search can fail with NUMA_NO_NODE,
which is not a valid index.

Fix it by checking that max_nid is a valid index.

[ mingo: Added changelog. ]

Fixes: 0fb3978b

 ("sched/numa: Fix NUMA topology for systems with CPU-less nodes")
Reported-by: Qian Cai <quic_qiancai@quicinc.com>
Tested-by: Qian Cai <quic_qiancai@quicinc.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Instead of declaring a struct page_vma_mapped_walk directly,
use these helpers to allow us to transition to a PFN approach in the
following patches.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

invalidate_inode_page() is the only caller of invalidate_complete_page()
and inlining it reveals that the first check is unnecessary (because we
hold the page locked, and we just retrieved the mapping from the page).
Actually, it does make a difference, in that tail pages no longer fail
at this check, so it's now possible to remove a tail page from a mapping.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

free_watch() does everything barring actually freeing the watch object.  Fix
this by adding the missing kfree.

kmemleak produces a report something like the following.  Note that as an
address can be seen in the first word, the watch would appear to have gone
through call_rcu().

BUG: memory leak
unreferenced object 0xffff88810ce4a200 (size 96):
  comm "syz-executor352", pid 3605, jiffies 4294947473 (age 13.720s)
  hex dump (first 32 bytes):
    e0 82 48 0d 81 88 ff ff 00 00 00 00 00 00 00 00  ..H.............
    80 a2 e4 0c 81 88 ff ff 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff8214e6cc>] kmalloc include/linux/slab.h:581 [inline]
    [<ffffffff8214e6cc>] kzalloc include/linux/slab.h:714 [inline]
    [<ffffffff8214e6cc>] keyctl_watch_key+0xec/0x2e0 security/keys/keyctl.c:1800
    [<ffffffff8214ec84>] __do_sys_keyctl+0x3c4/0x490 security/keys/keyctl.c:2016
    [<ffffffff84493a25>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
    [<ffffffff84493a25>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
    [<ffffffff84600068>] entry_SYSCALL_64_after_hwframe+0x44/0xae

Fixes: c73be61c

 ("pipe: Add general notification queue support")
Reported-and-tested-by:  <syzbot+6e2de48f06cdb2884bfc@syzkaller.appspotmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>

In watch_queue_set_size(), the error cleanup code doesn't take account of
the fact that __free_page() can't handle a NULL pointer when trying to free
up buffer pages that did get allocated.

Fix this by only calling __free_page() on the pages actually allocated.

Without the fix, this can lead to something like the following:

BUG: KASAN: null-ptr-deref in __free_pages+0x1f/0x1b0 mm/page_alloc.c:5473
Read of size 4 at addr 0000000000000034 by task syz-executor168/3599
...
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 __kasan_report mm/kasan/report.c:446 [inline]
 kasan_report.cold+0x66/0xdf mm/kasan/report.c:459
 check_region_inline mm/kasan/generic.c:183 [inline]
 kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
 instrument_atomic_read include/linux/instrumented.h:71 [inline]
 atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
 page_ref_count include/linux/page_ref.h:67 [inline]
 put_page_testzero include/linux/mm.h:717 [inline]
 __free_pages+0x1f/0x1b0 mm/page_alloc.c:5473
 watch_queue_set_size+0x499/0x630 kernel/watch_queue.c:275
 pipe_ioctl+0xac/0x2b0 fs/pipe.c:632
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Fixes: c73be61c

 ("pipe: Add general notification queue support")
Reported-and-tested-by:  <syzbot+d55757faa9b80590767b@syzkaller.appspotmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>

When an enum is used in the visible parts of a trace event that is
exported to user space, the user space applications like perf and
trace-cmd do not have a way to know what the value of the enum is. To
solve this, at boot up (or module load) the printk formats are modified to
replace the enum with their numeric value in the string output.

Array fields of the event are defined by [<nr-elements>] in the type
portion of the format file so that the user space parsers can correctly
parse the array into the appropriate size chunks. But in some trace
events, an enum is used in defining the size of the array, which once
again breaks the parsing of user space tooling.

This was solved the same way as the print formats were, but it modified
the type strings of the trace event. This caused crashes in some
architectures because, as supposed to the print string, is a const string
value. This was not detected on x86, as it appears that const strings are
still writable (at least in boot up), but other architectures this is not
the case, and writing to a const string will cause a kernel fault.

To fix this, use kstrdup() to copy the type before modifying it. If the
trace event is for the core kernel there's no need to free it because the
string will be in use for the life of the machine being on line. For
modules, create a link list to store all the strings being allocated for
modules and when the module is removed, free them.

Link: https://lore.kernel.org/all/yt9dr1706b4i.fsf@linux.ibm.com/
Link: https://lkml.kernel.org/r/20220318153432.3984b871@gandalf.local.home



Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Fixes: b3bc8547

 ("tracing: Have TRACE_DEFINE_ENUM affect trace event types as well")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Previously, I failed to realize that Kees' patch [1] has not been merged
into the mainline yet, and dropped DEBUG_INFO=y too eagerly from the
mainline.  As the results, "make debug.config" won't be able to flip
DEBUG_INFO=n from the existing .config.  This should close the gaps of a
few weeks before Kees' patch is there, and work regardless of their
merging status anyway.

Link: https://lore.kernel.org/all/20220125075126.891825-1-keescook@chromium.org/ [1]
Link: https://lkml.kernel.org/r/20220308153524.8618-1-quic_qiancai@quicinc.com


Signed-off-by: Qian Cai <quic_qiancai@quicinc.com>
Reported-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Tracefs by default is locked down heavily. System operators can open up
some files, such as user_events to a broader set of users. These users
do not have access within tracefs beyond just the user_event files. Due
to this restriction the trace_add_event_call/remove calls will silently
fail since the caller does not have permissions to create directories.

To fix this trace_add_event_call/remove calls will be issued with
override creds of the global root UID. Creds are reverted immediately
afterward.

Link: https://lkml.kernel.org/r/20220308222807.2040-1-beaub@linux.microsoft.com



Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

This header is not (yet) standalone.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

kzalloc virtual addresses do not work with SetPageReserved, use the actual
page virtual addresses instead via alloc_pages.

The issue is reported when booting with user_events and
DEBUG_VM_PGFLAGS=y.

Also make the number of events based on the ORDER.

Link: https://lore.kernel.org/all/CADYN=9+xY5Vku3Ws5E9S60SM5dCFfeGeRBkmDFbcxX0ZMoFing@mail.gmail.com/
Link: https://lore.kernel.org/all/20220311223028.1865-1-beaub@linux.microsoft.com/



Cc: Beau Belgrave <beaub@linux.microsoft.com>
Reported-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

watch_queue_clear() has a comment stating that setting ->defunct to true
preventing new additions as well as preventing notifications.  Whilst
the latter is true, the first bit is superfluous since at the time this
function is called, the pipe cannot be accessed to add new event
sources.

Remove the "new additions" bit from the comment.

Fixes: c73be61c

 ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

There's nothing to synchronise post_one_notification() versus
pipe_read().  Whilst posting is done under pipe->rd_wait.lock, the
reader only takes pipe->mutex which cannot bar notification posting as
that may need to be made from contexts that cannot sleep.

Fix this by setting pipe->head with a barrier in post_one_notification()
and reading pipe->head with a barrier in pipe_read().

If that's not sufficient, the rd_wait.lock will need to be taken,
possibly in a ->confirm() op so that it only applies to notifications.
The lock would, however, have to be dropped before copy_page_to_iter()
is invoked.

Fixes: c73be61c

 ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Free the watch_queue note allocation bitmap when the watch_queue is
destroyed.

Fixes: c73be61c

 ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Currently, watch_queue_set_size() sets the number of notes available in
wqueue->nr_notes according to the number of notes allocated, but sets
the size of the bitmap to the unrounded number of notes originally asked
for.

Fix this by setting the bitmap size to the number of notes we're
actually going to make available (ie. the number allocated).

Fixes: c73be61c

 ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Use bitmap_alloc() to simplify code, improve the semantic and reduce
some open-coded arithmetic in allocator arguments.

Also change a memset(0xff) into an equivalent bitmap_fill() to keep
consistency.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The pipe ring size must always be a power of 2 as the head and tail
pointers are masked off by AND'ing with the size of the ring - 1.
watch_queue_set_size(), however, lets you specify any number of notes
between 1 and 511.  This number is passed through to pipe_resize_ring()
without checking/forcing its alignment.

Fix this by rounding the number of slots required up to the nearest
power of two.  The request is meant to guarantee that at least that many
notifications can be generated before the queue is full, so rounding
down isn't an option, but, alternatively, it may be better to give an
error if we aren't allowed to allocate that much ring space.

Fixes: c73be61c

 ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When a pipe ring descriptor points to a notification message, the
refcount on the backing page is incremented by the generic get function,
but the release function, which marks the bitmap, doesn't drop the page
ref.

Fix this by calling generic_pipe_buf_release() at the end of
watch_queue_pipe_buf_release().

Fixes: c73be61c

 ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In watch_queue_set_filter(), there are a couple of places where we check
that the filter type value does not exceed what the type_filter bitmap
can hold.  One place calculates the number of bits by:

   if (tf[i].type >= sizeof(wfilter->type_filter) * 8)

which is fine, but the second does:

   if (tf[i].type >= sizeof(wfilter->type_filter) * BITS_PER_LONG)

which is not.  This can lead to a couple of out-of-bounds writes due to
a too-large type:

 (1) __set_bit() on wfilter->type_filter
 (2) Writing more elements in wfilter->filters[] than we allocated.

Fix this by just using the proper WATCH_TYPE__NR instead, which is the
number of types we actually know about.

The bug may cause an oops looking something like:

  BUG: KASAN: slab-out-of-bounds in watch_queue_set_filter+0x659/0x740
  Write of size 4 at addr ffff88800d2c66bc by task watch_queue_oob/611
  ...
  Call Trace:
   <TASK>
   dump_stack_lvl+0x45/0x59
   print_address_description.constprop.0+0x1f/0x150
   ...
   kasan_report.cold+0x7f/0x11b
   ...
   watch_queue_set_filter+0x659/0x740
   ...
   __x64_sys_ioctl+0x127/0x190
   do_syscall_64+0x43/0x90
   entry_SYSCALL_64_after_hwframe+0x44/0xae

  Allocated by task 611:
   kasan_save_stack+0x1e/0x40
   __kasan_kmalloc+0x81/0xa0
   watch_queue_set_filter+0x23a/0x740
   __x64_sys_ioctl+0x127/0x190
   do_syscall_64+0x43/0x90
   entry_SYSCALL_64_after_hwframe+0x44/0xae

  The buggy address belongs to the object at ffff88800d2c66a0
   which belongs to the cache kmalloc-32 of size 32
  The buggy address is located 28 bytes inside of
   32-byte region [ffff88800d2c66a0, ffff88800d2c66c0)

Fixes: c73be61c

 ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add ftrace_boot_snapshot kernel parameter that will take a snapshot at the
end of boot up just before switching over to user space (it happens during
the kernel freeing of init memory).

This is useful when there's interesting data that can be collected from
kernel start up, but gets overridden by user space start up code. With
this option, the ring buffer content from the boot up traces gets saved in
the snapshot at the end of boot up. This trace can be read from:

 /sys/kernel/tracing/snapshot

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

The macro TRACE_DEFINE_ENUM is used to convert enums in the kernel to
their actual value when they are exported to user space via the trace
event format file.

Currently only the enums in the "print fmt" (TP_printk in the TRACE_EVENT
macro) have the enums converted. But the enums can be used to denote array
size:

        field:unsigned int fc_ineligible_rc[EXT4_FC_REASON_MAX]; offset:12;      size:36;        signed:0;

The EXT4_FC_REASON_MAX has no meaning to userspace but it needs to know
that information to know how to parse the array.

Have the array indexes also be parsed as well.

Link: https://lore.kernel.org/all/cover.1646922487.git.riteshh@linux.ibm.com/



Reported-by: Ritesh Harjani <riteshh@linux.ibm.com>
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

0-day reported the strncpy error below:

../kernel/trace/trace_events_synth.c: In function 'last_cmd_set':
../kernel/trace/trace_events_synth.c:65:9: warning: 'strncpy' specified bound depends on the length o\
f the source argument [-Wstringop-truncation]
   65 |         strncpy(last_cmd, str, strlen(str) + 1);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../kernel/trace/trace_events_synth.c:65:32: note: length computed here
   65 |         strncpy(last_cmd, str, strlen(str) + 1);
      |                                ^~~~~~~~~~~

There's no reason to use strncpy here, in fact there's no reason to do
anything but a simple kstrdup() (note we don't even need to check for
failure since last_cmod is expected to be either the last cmd string
or NULL, and the containing function is a void return).

Link: https://lkml.kernel.org/r/77deca8cbfd226981b3f1eab203967381e9b5bd9.camel@kernel.org

Fixes: 27c888da

 ("tracing: Remove size restriction on synthetic event cmd error logging")

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Find user_events always while under the event_mutex and before leaving
the lock, add a ref count to the user_event. This ensures that all paths
under the event_mutex that check the ref counts will be synchronized.

The ioctl add/delete paths are protected by the reg_mutex. However,
dyn_event is only protected by the event_mutex. The dyn_event delete
path cannot acquire reg_mutex, since that could cause a deadlock between
the ioctl delete case acquiring event_mutex after acquiring the reg_mutex.

Link: https://lkml.kernel.org/r/20220310001141.1660-1-beaub@linux.microsoft.com



Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Allow custom events to be added to the events directory in the tracefs
file system. For example, a module could be installed that attaches to an
event and wants to be enabled and disabled via the tracefs file system. It
would use trace_add_event_call() to add the event to the tracefs
directory, and trace_remove_event_call() to remove it.

Make both those functions EXPORT_SYMBOL_GPL().

Link: https://lkml.kernel.org/r/20220303220625.186988045@goodmis.org



Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Using strnlen(dest, str, n) is confusing, as the size of dest must be
strlen(dest) + n + 1. Even more confusing, using sizeof(string constant)
gives you strlen(string constant) + 1 and not just strlen().

These two together made using strncat() with a constant string a bit off
in the calculations as we have:

	len = sizeof(HIST_PREFIX) + strlen(str) + 1;
	kfree(last_cmd);
	last_cmd = kzalloc(len, GFP_KERNEL);
	strcpy(last_cmd, HIST_PREFIX);
	len -= sizeof(HIST_PREFIX) + 1;
	strncat(last_cmd, str, len);

The above works if we s/sizeof/strlen/ with HIST_PREFIX (which is defined
as "hist:", but because sizeof(HIST_PREFIX) is equal to
strlen(HIST_PREFIX) + 1, we can drop the +1 in the code. But at least
comment that we are doing so.

Link: https://lore.kernel.org/all/202203082112.Iu7tvFl4-lkp@intel.com/

Fixes: 9f8e5aee

 ("tracing: Fix allocation of last_cmd in last_cmd_set()")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Ensure name is initialized by default to NULL to prevent possible edge
cases that could lead to it being left uninitialized. Add an explicit
check for NULL name to ensure edge boundaries.

Link: https://lore.kernel.org/bpf/20220224105334.GA2248@kili/
Link: https://lore.kernel.org/linux-trace-devel/20220224181637.2129-1-beaub@linux.microsoft.com



Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Clean up the following clang-w1 warning:

kernel/trace/ftrace.c:7827: warning: Function parameter or member 'ops'
not described in 'unregister_ftrace_function'.

kernel/trace/ftrace.c:7805: warning: Function parameter or member 'ops'
not described in 'register_ftrace_function'.

Link: https://lkml.kernel.org/r/20220307004303.26399-1-jiapeng.chong@linux.alibaba.com



Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

At the moment running osnoise on a nohz_full CPU or uncontested FIFO
priority and a PREEMPT_RCU kernel might have the side effect of
extending grace periods too much. This will entice RCU to force a
context switch on the wayward CPU to end the grace period, all while
introducing unwarranted noise into the tracer. This behaviour is
unavoidable as overly extending grace periods might exhaust the system's
memory.

This same exact problem is what extended quiescent states (EQS) were
created for, conversely, rcu_momentary_dyntick_idle() emulates them by
performing a zero duration EQS. So let's make use of it.

In the common case rcu_momentary_dyntick_idle() is fairly inexpensive:
atomically incrementing a local per-CPU counter and doing a store. So it
shouldn't affect osnoise's measurements (which has a 1us granularity),
so we'll call it unanimously.

The uncommon case involve calling rcu_momentary_dyntick_idle() after
having the osnoise process:

 - Receive an expedited quiescent state IPI with preemption disabled or
   during an RCU critical section. (activates rdp->cpu_no_qs.b.exp
   code-path).

 - Being preempted within in an RCU critical section and having the
   subsequent outermost rcu_read_unlock() called with interrupts
   disabled. (t->rcu_read_unlock_special.b.blocked code-path).

Neither of those are possible at the moment, and are unlikely to be in
the future given the osnoise's loop design. On top of this, the noise
generated by the situations described above is unavoidable, and if not
exposed by rcu_momentary_dyntick_idle() will be eventually seen in
subsequent rcu_read_unlock() calls or schedule operations.

Link: https://lkml.kernel.org/r/20220307180740.577607-1-nsaenzju@redhat.com

Cc: stable@vger.kernel.org
Fixes: bce29ac9

 ("trace: Add osnoise tracer")
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Nicolas reported that using:

 # trace-cmd record -e all -M 10 -p osnoise --poll

Resulted in the following kernel warning:

 ------------[ cut here ]------------
 WARNING: CPU: 0 PID: 1217 at kernel/tracepoint.c:404 tracepoint_probe_unregister+0x280/0x370
 [...]
 CPU: 0 PID: 1217 Comm: trace-cmd Not tainted 5.17.0-rc6-next-20220307-nico+ #19
 RIP: 0010:tracepoint_probe_unregister+0x280/0x370
 [...]
 CR2: 00007ff919b29497 CR3: 0000000109da4005 CR4: 0000000000170ef0
 Call Trace:
  <TASK>
  osnoise_workload_stop+0x36/0x90
  tracing_set_tracer+0x108/0x260
  tracing_set_trace_write+0x94/0xd0
  ? __check_object_size.part.0+0x10a/0x150
  ? selinux_file_permission+0x104/0x150
  vfs_write+0xb5/0x290
  ksys_write+0x5f/0xe0
  do_syscall_64+0x3b/0x90
  entry_SYSCALL_64_after_hwframe+0x44/0xae
 RIP: 0033:0x7ff919a18127
 [...]
 ---[ end trace 0000000000000000 ]---

The warning complains about an attempt to unregister an
unregistered tracepoint.

This happens on trace-cmd because it first stops tracing, and
then switches the tracer to nop. Which is equivalent to:

  # cd /sys/kernel/tracing/
  # echo osnoise > current_tracer
  # echo 0 > tracing_on
  # echo nop > current_tracer

The osnoise tracer stops the workload when no trace instance
is actually collecting data. This can be caused both by
disabling tracing or disabling the tracer itself.

To avoid unregistering events twice, use the existing
trace_osnoise_callback_enabled variable to check if the events
(and the workload) are actually active before trying to
deactivate them.

Link: https://lore.kernel.org/all/c898d1911f7f9303b7e14726e7cc9678fbfb4a0e.camel@redhat.com/
Link: https://lkml.kernel.org/r/938765e17d5a781c2df429a98f0b2e7cc317b022.1646823913.git.bristot@kernel.org

Cc: stable@vger.kernel.org
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Fixes: 2fac8d64

 ("tracing/osnoise: Allow multiple instances of the same tracer")
Reported-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

While investigating the sparse warning reported by the LKP bot [1],
observed that we have a redundant variable "top" in the function
build_sched_domains that was introduced in the recent commit
e496132e ("sched/fair: Adjust the allowed NUMA imbalance when
SD_NUMA spans multiple LLCs")

The existing variable "sd" suffices which allows us to remove the
redundant variable "top" while annotating the other variable "top_p"
with the "__rcu" annotation to silence the sparse warning.

[1] https://lore.kernel.org/lkml/202202170853.9vofgC3O-lkp@intel.com/

Fixes: e496132e

 ("sched/fair: Adjust the allowed NUMA imbalance when SD_NUMA spans multiple LLCs")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lore.kernel.org/r/20220218162743.1134-1-kprateek.nayak@amd.com

The `struct rq *rq` parameter isn't used. Remove it.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20220302183433.333029-7-dietmar.eggemann@arm.com

The need_pull_[rt|dl]_task() and pull_[rt|dl]_task() functions are not
used on a !CONFIG_SMP system. Remove them.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20220302183433.333029-6-dietmar.eggemann@arm.com

Deploy __node_2_pdl(node), __node_2_dle(node) and rb_first_cached()
consistently throughout the sched class source file which makes the
code at least easier to read.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20220302183433.333029-5-dietmar.eggemann@arm.com

Both functions are doing almost the same, that is checking if admission
control is still respected.

With exclusive cpusets, dl_task_can_attach() checks if the destination
cpuset (i.e. its root domain) has enough CPU capacity to accommodate the
task.
dl_cpu_busy() checks if there is enough CPU capacity in the cpuset in
case the CPU is hot-plugged out.

dl_task_can_attach() is used to check if a task can be admitted while
dl_cpu_busy() is used to check if a CPU can be hotplugged out.

Make dl_cpu_busy() able to deal with a task and use it instead of
dl_task_can_attach() in task_can_attach().

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20220302183433.333029-4-dietmar.eggemann@arm.com

Move the deadline bandwidth management (admission control) functions
__dl_add(), __dl_sub() and __dl_overflow() as well as the bandwidth
reclaim function __dl_update() from private task scheduler header file
to the deadline sched class source file.
The functions are only used internally so they don't have to be
exported.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20220302183433.333029-3-dietmar.eggemann@arm.com

Since commit 1724813d

 ("sched/deadline: Remove the sysctl_sched_dl
knobs") the default deadline bandwidth control structure has no purpose.
Remove it.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20220302183433.333029-2-dietmar.eggemann@arm.com

RCU_SOFTIRQ used to be special in that it could be raised on purpose
within the idle path to prevent from stopping the tick. Some code still
prevents from unnecessary warnings related to this specific behaviour
while entering in dynticks-idle mode.

However the nohz layout has changed quite a bit in ten years, and the
removal of CONFIG_RCU_FAST_NO_HZ has been the final straw to this
safe-conduct. Now the RCU_SOFTIRQ vector is expected to be raised from
sane places.

A remaining corner case is admitted though when the vector is invoked
in fragile hotplug path.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Paul Menzel <pmenzel@molgen.mpg.de>

With the removal of CONFIG_RCU_FAST_NO_HZ, the parameters in
rcu_needs_cpu() are not necessary anymore. Simply remove them.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Paul Menzel <pmenzel@molgen.mpg.de>