Commit Graph

41809 Commits

Author SHA1 Message Date
Linus Torvalds 8b817fded4 Tracing fixes:
User events:
 
  - Use long instead of int for storing the enable set/clear bit, as it was
    found that big endian machines could end up using the wrong bits.
 
  - Split allocating mm and attaching it. This keeps the allocation separate
    from the registration and avoids various races.
 
  - Remove RCU locking around pin_user_pages_remote() as that can schedule. The
    RCU protection is no longer needed with the above split of mm allocation and
    attaching.
 
  - Rename the "link" fields of the various structs to something more
    meaningful.
 
  - Add comments around user_event_mm struct usage and locking requirements.
 
 Timerlat tracer:
 
  - Fix missed wakeup of timerlat thread caused by the timerlat interrupt
    triggering when tracing is off. The timer interrupt handler needs to always
    wake up the timerlat thread regardless if tracing is enabled or not,
    otherwise, it will never wake up.
 
 Histograms:
 
  - Fix regression of breaking the "stacktrace" modifier for variables. That
    modifier cannot be used for values, but can be used for variables that are
    passed from one histogram to the next. This was broken when adding the
    restriction to values as the variable logic used the same code.
 
  - Rename the special field "stacktrace" to "common_stacktrace". Special fields
    (that are not actually part of the event, but can act just like event
    fields, like 'comm' and 'timestamp') should be prefixed with 'common_' for
    consistency. To keep backward compatibility, 'stacktrace' can still be used
    (as with the special field 'cpu'), but can be overridden if the event has a
    field called 'stacktrace'.
 
  - Update the synthetic event selftests to use the new name (synthetic events
    are created by histograms)
 
 Tracing bootup selftests:
 
  - Reorganize the code to keep artifacts of the selftests not compiled in when
    selftests are not configured.
 
  - Add various cond_resched() around the selftest code, as the softlock
    watchdog was triggering much more often. It appears that the kernel runs
    slower now with full debugging enabled.
 
  - While debugging ftrace with ftrace (using an instance ring buffer instead of
    the top level one), I found that the selftests were disabling prints to the
    debug instance. This should not happen, as the selftests only disable
    printing to the main buffer as the selftests examine the main buffer to see
    if it has what it expects, and prints can make the tests fail. Make the
    selftests only disable printing to the toplevel buffer, and leave the
    instance buffers alone.
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Merge tag 'trace-v6.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:
 "User events:

   - Use long instead of int for storing the enable set/clear bit, as it
     was found that big endian machines could end up using the wrong
     bits.

   - Split allocating mm and attaching it. This keeps the allocation
     separate from the registration and avoids various races.

   - Remove RCU locking around pin_user_pages_remote() as that can
     schedule. The RCU protection is no longer needed with the above
     split of mm allocation and attaching.

   - Rename the "link" fields of the various structs to something more
     meaningful.

   - Add comments around user_event_mm struct usage and locking
     requirements.

  Timerlat tracer:

   - Fix missed wakeup of timerlat thread caused by the timerlat
     interrupt triggering when tracing is off. The timer interrupt
     handler needs to always wake up the timerlat thread regardless if
     tracing is enabled or not, otherwise, it will never wake up.

  Histograms:

   - Fix regression of breaking the "stacktrace" modifier for variables.
     That modifier cannot be used for values, but can be used for
     variables that are passed from one histogram to the next. This was
     broken when adding the restriction to values as the variable logic
     used the same code.

   - Rename the special field "stacktrace" to "common_stacktrace".

     Special fields (that are not actually part of the event, but can
     act just like event fields, like 'comm' and 'timestamp') should be
     prefixed with 'common_' for consistency. To keep backward
     compatibility, 'stacktrace' can still be used (as with the special
     field 'cpu'), but can be overridden if the event has a field called
     'stacktrace'.

   - Update the synthetic event selftests to use the new name (synthetic
     events are created by histograms)

  Tracing bootup selftests:

   - Reorganize the code to keep artifacts of the selftests not compiled
     in when selftests are not configured.

   - Add various cond_resched() around the selftest code, as the
     softlock watchdog was triggering much more often. It appears that
     the kernel runs slower now with full debugging enabled.

   - While debugging ftrace with ftrace (using an instance ring buffer
     instead of the top level one), I found that the selftests were
     disabling prints to the debug instance.

     This should not happen, as the selftests only disable printing to
     the main buffer as the selftests examine the main buffer to see if
     it has what it expects, and prints can make the tests fail.

     Make the selftests only disable printing to the toplevel buffer,
     and leave the instance buffers alone"

* tag 'trace-v6.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Have function_graph selftest call cond_resched()
  tracing: Only make selftest conditionals affect the global_trace
  tracing: Make tracing_selftest_running/delete nops when not used
  tracing: Have tracer selftests call cond_resched() before running
  tracing: Move setting of tracing_selftest_running out of register_tracer()
  tracing/selftests: Update synthetic event selftest to use common_stacktrace
  tracing: Rename stacktrace field to common_stacktrace
  tracing/histograms: Allow variables to have some modifiers
  tracing/user_events: Document user_event_mm one-shot list usage
  tracing/user_events: Rename link fields for clarity
  tracing/user_events: Remove RCU lock while pinning pages
  tracing/user_events: Split up mm alloc and attach
  tracing/timerlat: Always wakeup the timerlat thread
  tracing/user_events: Use long vs int for atomic bit ops
2023-05-29 07:20:13 -04:00
Linus Torvalds ac2263b588 Revert "module: error out early on concurrent load of the same module file"
This reverts commit 9828ed3f69.

Sadly, it does seem to cause failures to load modules. Johan Hovold reports:

 "This change breaks module loading during boot on the Lenovo Thinkpad
  X13s (aarch64).

  Specifically it results in indefinite probe deferral of the display
  and USB (ethernet) which makes it a pain to debug. Typing in the dark
  to acquire some logs reveals that other modules are missing as well"

Since this was applied late as a "let's try this", I'm reverting it
asap, and we can try to figure out what goes wrong later.  The excessive
parallel module loading problem is annoying, but not noticeable in
normal situations, and this was only meant as an optimistic workaround
for a user-space bug.

One possible solution may be to do the optimistic exclusive open first,
and then use a lock to serialize loading if that fails.

Reported-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/lkml/ZHRpH-JXAxA6DnzR@hovoldconsulting.com/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-05-29 06:40:33 -04:00
Steven Rostedt (Google) a2d910f022 tracing: Have function_graph selftest call cond_resched()
When all kernel debugging is enabled (lockdep, KSAN, etc), the function
graph enabling and disabling can take several seconds to complete. The
function_graph selftest enables and disables function graph tracing
several times. With full debugging enabled, the soft lockup watchdog was
triggering because the selftest was running without ever scheduling.

Add cond_resched() throughout the test to make sure it does not trigger
the soft lockup detector.

Link: https://lkml.kernel.org/r/20230528051742.1325503-6-rostedt@goodmis.org

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-28 21:15:46 -04:00
Steven Rostedt (Google) ac9d2cb1d5 tracing: Only make selftest conditionals affect the global_trace
The tracing_selftest_running and tracing_selftest_disabled variables were
to keep trace_printk() and other writes from affecting the tracing
selftests, as the tracing selftests would examine the ring buffer to see
if it contained what it expected or not. trace_printk() and friends could
add to the ring buffer and cause the selftests to fail (and then disable
the tracer that was being tested). To keep that from happening, these
variables were added and would keep trace_printk() and friends from
writing to the ring buffer while the tests were going on.

But this was only the top level ring buffer (owned by the global_trace
instance). There is no reason to prevent writing into ring buffers of
other instances via the trace_array_printk() and friends. For the
functions that could be used by other instances, check if the global_trace
is the tracer instance that is being written to before deciding to not
allow the write.

Link: https://lkml.kernel.org/r/20230528051742.1325503-5-rostedt@goodmis.org

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-28 21:15:33 -04:00
Steven Rostedt (Google) a3ae76d7ff tracing: Make tracing_selftest_running/delete nops when not used
There's no reason to test the condition variables tracing_selftest_running
or tracing_selftest_delete when tracing selftests are not enabled. Make
them define 0s when not the selftests are not configured in.

Link: https://lkml.kernel.org/r/20230528051742.1325503-4-rostedt@goodmis.org

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-28 21:15:26 -04:00
Steven Rostedt (Google) 9da705d432 tracing: Have tracer selftests call cond_resched() before running
As there are more and more internal selftests being added to the Linux
kernel (KSAN, lockdep, etc) the selftests are taking longer to run when
these are enabled. Add a cond_resched() to the calling of
do_run_tracer_selftest() to force a schedule if NEED_RESCHED is set,
otherwise the soft lockup watchdog may trigger on boot up.

Link: https://lkml.kernel.org/r/20230528051742.1325503-3-rostedt@goodmis.org

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-28 21:15:17 -04:00
Steven Rostedt (Google) e8352cf577 tracing: Move setting of tracing_selftest_running out of register_tracer()
The variables tracing_selftest_running and tracing_selftest_disabled are
only used for when CONFIG_FTRACE_STARTUP_TEST is enabled. Make them only
visible within the selftest code. The setting of those variables are in
the register_tracer() call, and set in a location where they do not need
to be. Create a wrapper around run_tracer_selftest() called
do_run_tracer_selftest() which sets those variables, and have
register_tracer() call that instead.

Having those variables only set within the CONFIG_FTRACE_STARTUP_TEST
scope gets rid of them (and also the ability to remove testing against
them) when the startup tests are not enabled (most cases).

Link: https://lkml.kernel.org/r/20230528051742.1325503-2-rostedt@goodmis.org

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-28 21:15:04 -04:00
Linus Torvalds d8f14b84fe Two fixes for debugobjects:
- Prevent that the allocation path wakes up kswapd. That's a long
     standing issue due to the GFP_ATOMIC allocation flag. As debug objects
     can be invoked from pretty much any context waking kswapd can end up
     in arbitrary lock chains versus the waitqueue lock.
 
   - Correct the explicit lockdep wait-type violation in
     debug_object_fill_pool().
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Merge tag 'core-debugobjects-2023-05-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull debugobjects fixes from Thomas Gleixner:
 "Two fixes for debugobjects:

   - Prevent the allocation path from waking up kswapd.

     That's a long standing issue due to the GFP_ATOMIC allocation flag.
     As debug objects can be invoked from pretty much any context waking
     kswapd can end up in arbitrary lock chains versus the waitqueue
     lock

   - Correct the explicit lockdep wait-type violation in
     debug_object_fill_pool()"

* tag 'core-debugobjects-2023-05-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  debugobjects: Don't wake up kswapd from fill_pool()
  debugobjects,locking: Annotate debug_object_fill_pool() wait type violation
2023-05-28 07:15:33 -04:00
Linus Torvalds 4e893b5aa4 xen: branch for v6.4-rc4
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Merge tag 'for-linus-6.4-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen fixes from Juergen Gross:

 - a double free fix in the Xen pvcalls backend driver

 - a fix for a regression causing the MSI related sysfs entries to not
   being created in Xen PV guests

 - a fix in the Xen blkfront driver for handling insane input data
   better

* tag 'for-linus-6.4-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  x86/pci/xen: populate MSI sysfs entries
  xen/pvcalls-back: fix double frees with pvcalls_new_active_socket()
  xen/blkfront: Only check REQ_FUA for writes
2023-05-27 09:42:56 -07:00
Linus Torvalds 9828ed3f69 module: error out early on concurrent load of the same module file
It turns out that udev under certain circumstances will concurrently try
to load the same modules over-and-over excessively.  This isn't a kernel
bug, but it ends up affecting the kernel, to the point that under
certain circumstances we can fail to boot, because the kernel uses a lot
of memory to read all the module data all at once.

Note that it isn't a memory leak, it's just basically a thundering herd
problem happening at bootup with a lot of CPUs, with the worst cases
then being pretty bad.

Admittedly the worst situations are somewhat contrived: lots and lots of
CPUs, not a lot of memory, and KASAN enabled to make it all slower and
as such (unintentionally) exacerbate the problem.

Luis explains: [1]

 "My best assessment of the situation is that each CPU in udev ends up
  triggering a load of duplicate set of modules, not just one, but *a
  lot*. Not sure what heuristics udev uses to load a set of modules per
  CPU."

Petr Pavlu chimes in: [2]

 "My understanding is that udev workers are forked. An initial kmod
  context is created by the main udevd process but no sharing happens
  after the fork. It means that the mentioned memory pool logic doesn't
  really kick in.

  Multiple parallel load requests come from multiple udev workers, for
  instance, each handling an udev event for one CPU device and making
  the exactly same requests as all others are doing at the same time.

  The optimization idea would be to recognize these duplicate requests
  at the udevd/kmod level and converge them"

Note that module loading has tried to mitigate this issue before, see
for example commit 064f4536d1 ("module: avoid allocation if module is
already present and ready"), which has a few ASCII graphs on memory use
due to this same issue.

However, while that noticed that the module was already loaded, and
exited with an error early before spending any more time on setting up
the module, it didn't handle the case of multiple concurrent module
loads all being active - but not complete - at the same time.

Yes, one of them will eventually win the race and finalize its copy, and
the others will then notice that the module already exists and error
out, but while this all happens, we have tons of unnecessary concurrent
work being done.

Again, the real fix is for udev to not do that (maybe it should use
threads instead of fork, and have actual shared data structures and not
cause duplicate work). That real fix is apparently not trivial.

But it turns out that the kernel already has a pretty good model for
dealing with concurrent access to the same file: the i_writecount of the
inode.

In fact, the module loading already indirectly uses 'i_writecount' ,
because 'kernel_file_read()' will in fact do

	ret = deny_write_access(file);
	if (ret)
		return ret;
	...
	allow_write_access(file);

around the read of the file data.  We do not allow concurrent writes to
the file, and return -ETXTBUSY if the file was open for writing at the
same time as the module data is loaded from it.

And the solution to the reader concurrency problem is to simply extend
this "no concurrent writers" logic to simply be "exclusive access".

Note that "exclusive" in this context isn't really some absolute thing:
it's only exclusion from writers and from other "special readers" that
do this writer denial.  So we simply introduce a variation of that
"deny_write_access()" logic that not only denies write access, but also
requires that this is the _only_ such access that denies write access.

Which means that you can't start loading a module that is already being
loaded as a module by somebody else, or you will get the same -ETXTBSY
error that you would get if there were writers around.

[ It also means that you can't try to load a currently executing
  executable as a module, for the same reason: executables do that same
  "deny_write_access()" thing, and that's obviously where the whole
  ETXTBSY logic traditionally came from.

  This is not a problem for kernel modules, since the set of normal
  executable files and kernel module files is entirely disjoint. ]

This new function is called "exclusive_deny_write_access()", and the
implementation is trivial, in that it's just an atomic decrement of
i_writecount if it was 0 before.

To use that new exclusivity check, all we then do is wrap the module
loading with that exclusive_deny_write_access()() / allow_write_access()
pair.  The actual patch is a bit bigger than that, because we want to
surround not just the "load file data" part, but the whole module setup,
to get maximum exclusion.

So this ends up splitting up "finit_module()" into a few helper
functions to make it all very clear and legible.

In Luis' test-case (bringing up 255 vcpu's in a virtual machine [3]),
the "wasted vmalloc" space (ie module data read into a vmalloc'ed area
in order to be loaded as a module, but then discarded because somebody
else loaded the same module instead) dropped from 1.8GiB to 474kB.  Yes,
that's gigabytes to kilobytes.

It doesn't drop completely to zero, because even with this change, you
can still end up having completely serial pointless module loads, where
one udev process has loaded a module fully (and thus the kernel has
released that exclusive lock on the module file), and then another udev
process tries to load the same module again.

So while we cannot fully get rid of the fundamental bug in user space,
we _can_ get rid of the excessive concurrent thundering herd effect.

A couple of final side notes on this all:

 - This tweak only affects the "finit_module()" system call, which gives
   the kernel a file descriptor with the module data.

   You can also just feed the module data as raw data from user space
   with "init_module()" (note the lack of 'f' at the beginning), and
   obviously for that case we do _not_ have any "exclusive read" logic.

   So if you absolutely want to do things wrong in user space, and try
   to load the same module multiple times, and error out only later when
   the kernel ends up saying "you can't load the same module name
   twice", you can still do that.

   And in fact, some distros will do exactly that, because they will
   uncompress the kernel module data in user space before feeding it to
   the kernel (mainly because they haven't started using the new kernel
   side decompression yet).

   So this is not some absolute "you can't do concurrent loads of the
   same module". It's literally just a very simple heuristic that will
   catch it early in case you try to load the exact same module file at
   the same time, and in that case avoid a potentially nasty situation.

 - There is another user of "deny_write_access()": the verity code that
   enables fs-verity on a file (the FS_IOC_ENABLE_VERITY ioctl).

   If you use fs-verity and you care about verifying the kernel modules
   (which does make sense), you should do it *before* loading said
   kernel module. That may sound obvious, but now the implementation
   basically requires it. Because if you try to do it concurrently, the
   kernel may refuse to load the module file that is being set up by the
   fs-verity code.

 - This all will obviously mean that if you insist on loading the same
   module in parallel, only one module load will succeed, and the others
   will return with an error.

   That was true before too, but what is different is that the -ETXTBSY
   error can be returned *before* the success case of another process
   fully loading and instantiating the module.

   Again, that might sound obvious, and it is indeed the whole point of
   the whole change: we are much quicker to notice the whole "you're
   already in the process of loading this module".

   So it's very much intentional, but it does mean that if you just
   spray the kernel with "finit_module()", and expect that the module is
   immediately loaded afterwards without checking the return value, you
   are doing something horribly horribly wrong.

   I'd like to say that that would never happen, but the whole _reason_
   for this commit is that udev is currently doing something horribly
   horribly wrong, so ...

Link: https://lore.kernel.org/all/ZEGopJ8VAYnE7LQ2@bombadil.infradead.org/ [1]
Link: https://lore.kernel.org/all/23bd0ce6-ef78-1cd8-1f21-0e706a00424a@suse.com/ [2]
Link: https://lore.kernel.org/lkml/ZG%2Fa+nrt4%2FAAUi5z@bombadil.infradead.org/ [3]
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Tested-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-05-25 17:07:57 -07:00
Linus Torvalds 50fb587e6a Networking fixes for 6.4-rc4, including fixes from bluetooth and bpf
Current release - regressions:
 
   - net: fix skb leak in __skb_tstamp_tx()
 
   - eth: mtk_eth_soc: fix QoS on DSA MAC on non MTK_NETSYS_V2 SoCs
 
 Current release - new code bugs:
 
   - handshake:
     - fix sock->file allocation
     - fix handshake_dup() ref counting
 
   - bluetooth:
     - fix potential double free caused by hci_conn_unlink
     - fix UAF in hci_conn_hash_flush
 
 Previous releases - regressions:
 
   - core: fix stack overflow when LRO is disabled for virtual interfaces
 
   - tls: fix strparser rx issues
 
   - bpf:
     - fix many sockmap/TCP related issues
     - fix a memory leak in the LRU and LRU_PERCPU hash maps
     - init the offload table earlier
 
   - eth: mlx5e:
     - do as little as possible in napi poll when budget is 0
     - fix using eswitch mapping in nic mode
     - fix deadlock in tc route query code
 
 Previous releases - always broken:
 
   - udplite: fix NULL pointer dereference in __sk_mem_raise_allocated()
 
   - raw: fix output xfrm lookup wrt protocol
 
   - smc: reset connection when trying to use SMCRv2 fails
 
   - phy: mscc: enable VSC8501/2 RGMII RX clock
 
   - eth: octeontx2-pf: fix TSOv6 offload
 
   - eth: cdc_ncm: deal with too low values of dwNtbOutMaxSize
 
 Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Merge tag 'net-6.4-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

Pull networking fixes from Paolo Abeni:
 "Including fixes from bluetooth and bpf.

  Current release - regressions:

   - net: fix skb leak in __skb_tstamp_tx()

   - eth: mtk_eth_soc: fix QoS on DSA MAC on non MTK_NETSYS_V2 SoCs

  Current release - new code bugs:

   - handshake:
      - fix sock->file allocation
      - fix handshake_dup() ref counting

   - bluetooth:
      - fix potential double free caused by hci_conn_unlink
      - fix UAF in hci_conn_hash_flush

  Previous releases - regressions:

   - core: fix stack overflow when LRO is disabled for virtual
     interfaces

   - tls: fix strparser rx issues

   - bpf:
      - fix many sockmap/TCP related issues
      - fix a memory leak in the LRU and LRU_PERCPU hash maps
      - init the offload table earlier

   - eth: mlx5e:
      - do as little as possible in napi poll when budget is 0
      - fix using eswitch mapping in nic mode
      - fix deadlock in tc route query code

  Previous releases - always broken:

   - udplite: fix NULL pointer dereference in __sk_mem_raise_allocated()

   - raw: fix output xfrm lookup wrt protocol

   - smc: reset connection when trying to use SMCRv2 fails

   - phy: mscc: enable VSC8501/2 RGMII RX clock

   - eth: octeontx2-pf: fix TSOv6 offload

   - eth: cdc_ncm: deal with too low values of dwNtbOutMaxSize"

* tag 'net-6.4-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (79 commits)
  udplite: Fix NULL pointer dereference in __sk_mem_raise_allocated().
  net: phy: mscc: enable VSC8501/2 RGMII RX clock
  net: phy: mscc: remove unnecessary phydev locking
  net: phy: mscc: add support for VSC8501
  net: phy: mscc: add VSC8502 to MODULE_DEVICE_TABLE
  net/handshake: Enable the SNI extension to work properly
  net/handshake: Unpin sock->file if a handshake is cancelled
  net/handshake: handshake_genl_notify() shouldn't ignore @flags
  net/handshake: Fix uninitialized local variable
  net/handshake: Fix handshake_dup() ref counting
  net/handshake: Remove unneeded check from handshake_dup()
  ipv6: Fix out-of-bounds access in ipv6_find_tlv()
  net: ethernet: mtk_eth_soc: fix QoS on DSA MAC on non MTK_NETSYS_V2 SoCs
  docs: netdev: document the existence of the mail bot
  net: fix skb leak in __skb_tstamp_tx()
  r8169: Use a raw_spinlock_t for the register locks.
  page_pool: fix inconsistency for page_pool_ring_[un]lock()
  bpf, sockmap: Test progs verifier error with latest clang
  bpf, sockmap: Test FIONREAD returns correct bytes in rx buffer with drops
  bpf, sockmap: Test FIONREAD returns correct bytes in rx buffer
  ...
2023-05-25 10:55:26 -07:00
Jakub Kicinski 0c615f1cc3 bpf-for-netdev
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2023-05-24

We've added 19 non-merge commits during the last 10 day(s) which contain
a total of 20 files changed, 738 insertions(+), 448 deletions(-).

The main changes are:

1) Batch of BPF sockmap fixes found when running against NGINX TCP tests,
   from John Fastabend.

2) Fix a memleak in the LRU{,_PERCPU} hash map when bucket locking fails,
   from Anton Protopopov.

3) Init the BPF offload table earlier than just late_initcall,
   from Jakub Kicinski.

4) Fix ctx access mask generation for 32-bit narrow loads of 64-bit fields,
   from Will Deacon.

5) Remove a now unsupported __fallthrough in BPF samples,
   from Andrii Nakryiko.

6) Fix a typo in pkg-config call for building sign-file,
   from Jeremy Sowden.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  bpf, sockmap: Test progs verifier error with latest clang
  bpf, sockmap: Test FIONREAD returns correct bytes in rx buffer with drops
  bpf, sockmap: Test FIONREAD returns correct bytes in rx buffer
  bpf, sockmap: Test shutdown() correctly exits epoll and recv()=0
  bpf, sockmap: Build helper to create connected socket pair
  bpf, sockmap: Pull socket helpers out of listen test for general use
  bpf, sockmap: Incorrectly handling copied_seq
  bpf, sockmap: Wake up polling after data copy
  bpf, sockmap: TCP data stall on recv before accept
  bpf, sockmap: Handle fin correctly
  bpf, sockmap: Improved check for empty queue
  bpf, sockmap: Reschedule is now done through backlog
  bpf, sockmap: Convert schedule_work into delayed_work
  bpf, sockmap: Pass skb ownership through read_skb
  bpf: fix a memory leak in the LRU and LRU_PERCPU hash maps
  bpf: Fix mask generation for 32-bit narrow loads of 64-bit fields
  samples/bpf: Drop unnecessary fallthrough
  bpf: netdev: init the offload table earlier
  selftests/bpf: Fix pkg-config call building sign-file
====================

Link: https://lore.kernel.org/r/20230524170839.13905-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-05-24 21:57:57 -07:00
Maximilian Heyne 335b422346 x86/pci/xen: populate MSI sysfs entries
Commit bf5e758f02 ("genirq/msi: Simplify sysfs handling") reworked the
creation of sysfs entries for MSI IRQs. The creation used to be in
msi_domain_alloc_irqs_descs_locked after calling ops->domain_alloc_irqs.
Then it moved into __msi_domain_alloc_irqs which is an implementation of
domain_alloc_irqs. However, Xen comes with the only other implementation
of domain_alloc_irqs and hence doesn't run the sysfs population code
anymore.

Commit 6c796996ee ("x86/pci/xen: Fixup fallout from the PCI/MSI
overhaul") set the flag MSI_FLAG_DEV_SYSFS for the xen msi_domain_info
but that doesn't actually have an effect because Xen uses it's own
domain_alloc_irqs implementation.

Fix this by making use of the fallback functions for sysfs population.

Fixes: bf5e758f02 ("genirq/msi: Simplify sysfs handling")
Signed-off-by: Maximilian Heyne <mheyne@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20230503131656.15928-1-mheyne@amazon.de
Signed-off-by: Juergen Gross <jgross@suse.com>
2023-05-24 18:08:49 +02:00
Steven Rostedt (Google) 4b512860bd tracing: Rename stacktrace field to common_stacktrace
The histogram and synthetic events can use a pseudo event called
"stacktrace" that will create a stacktrace at the time of the event and
use it just like it was a normal field. We have other pseudo events such
as "common_cpu" and "common_timestamp". To stay consistent with that,
convert "stacktrace" to "common_stacktrace". As this was used in older
kernels, to keep backward compatibility, this will act just like
"common_cpu" did with "cpu". That is, "cpu" will be the same as
"common_cpu" unless the event has a "cpu" field. In which case, the
event's field is used. The same is true with "stacktrace".

Also update the documentation to reflect this change.

Link: https://lore.kernel.org/linux-trace-kernel/20230523230913.6860e28d@rorschach.local.home

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-23 23:38:23 -04:00
Steven Rostedt (Google) e30fbc618e tracing/histograms: Allow variables to have some modifiers
Modifiers are used to change the behavior of keys. For instance, they
can grouped into buckets, converted to syscall names (from the syscall
identifier), show task->comm of the current pid, be an array of longs
that represent a stacktrace, and more.

It was found that nothing stopped a value from taking a modifier. As
values are simple counters. If this happened, it would call code that
was not expecting a modifier and crash the kernel. This was fixed by
having the ___create_val_field() function test if a modifier was present
and fail if one was. This fixed the crash.

Now there's a problem with variables. Variables are used to pass fields
from one event to another. Variables are allowed to have some modifiers,
as the processing may need to happen at the time of the event (like
stacktraces and comm names of the current pid). The issue is that it too
uses __create_val_field(). Now that fails on modifiers, variables can no
longer use them (this is a regression).

As not all modifiers are for variables, have them use a separate check.

Link: https://lore.kernel.org/linux-trace-kernel/20230523221108.064a5d82@rorschach.local.home

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes: e0213434fe ("tracing: Do not let histogram values have some modifiers")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-23 22:56:55 -04:00
Beau Belgrave ff9e1632d6 tracing/user_events: Document user_event_mm one-shot list usage
During 6.4 development it became clear that the one-shot list used by
the user_event_mm's next field was confusing to others. It is not clear
how this list is protected or what the next field usage is for unless
you are familiar with the code.

Add comments into the user_event_mm struct indicating lock requirement
and usage. Also document how and why this approach was used via comments
in both user_event_enabler_update() and user_event_mm_get_all() and the
rules to properly use it.

Link: https://lkml.kernel.org/r/20230519230741.669-5-beaub@linux.microsoft.com
Link: https://lore.kernel.org/linux-trace-kernel/CAHk-=wicngggxVpbnrYHjRTwGE0WYscPRM+L2HO2BF8ia1EXgQ@mail.gmail.com/

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-23 21:08:33 -04:00
Beau Belgrave dcbd1ac266 tracing/user_events: Rename link fields for clarity
Currently most list_head fields of various structs within user_events
are simply named link. This causes folks to keep additional context in
their head when working with the code, which can be confusing.

Instead of using link, describe what the actual link is, for example:
list_del_rcu(&mm->link);

Changes into:
list_del_rcu(&mm->mms_link);

The reader now is given a hint the link is to the mms global list
instead of having to remember or spot check within the code.

Link: https://lkml.kernel.org/r/20230519230741.669-4-beaub@linux.microsoft.com
Link: https://lore.kernel.org/linux-trace-kernel/CAHk-=wicngggxVpbnrYHjRTwGE0WYscPRM+L2HO2BF8ia1EXgQ@mail.gmail.com/

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-23 21:08:33 -04:00
Linus Torvalds aaecdaf922 tracing/user_events: Remove RCU lock while pinning pages
pin_user_pages_remote() can reschedule which means we cannot hold any
RCU lock while using it. Now that enablers are not exposed out to the
tracing register callbacks during fork(), there is clearly no need to
require the RCU lock as event_mutex is enough to protect changes.

Remove unneeded RCU usages when pinning pages and walking enablers with
event_mutex held. Cleanup a misleading "safe" list walk that is not
needed. During fork() duplication, remove unneeded RCU list add, since
the list is not exposed yet.

Link: https://lkml.kernel.org/r/20230519230741.669-3-beaub@linux.microsoft.com
Link: https://lore.kernel.org/linux-trace-kernel/CAHk-=wiiBfT4zNS29jA0XEsy8EmbqTH1hAPdRJCDAJMD8Gxt5A@mail.gmail.com/

Fixes: 7235759084 ("tracing/user_events: Use remote writes for event enablement")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ change log written by Beau Belgrave ]
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-23 21:05:04 -04:00
Linus Torvalds 3e0fea09b1 tracing/user_events: Split up mm alloc and attach
When a new mm is being created in a fork() path it currently is
allocated and then attached in one go. This leaves the mm exposed out to
the tracing register callbacks while any parent enabler locations are
copied in. This should not happen.

Split up mm alloc and attach as unique operations. When duplicating
enablers, first alloc, then duplicate, and only upon success, attach.
This prevents any timing window outside of the event_reg mutex for
enablement walking. This allows for dropping RCU requirement for
enablement walking in later patches.

Link: https://lkml.kernel.org/r/20230519230741.669-2-beaub@linux.microsoft.com
Link: https://lore.kernel.org/linux-trace-kernel/CAHk-=whTBvXJuoi_kACo3qi5WZUmRrhyA-_=rRFsycTytmB6qw@mail.gmail.com/

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ change log written by Beau Belgrave ]
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-23 20:58:17 -04:00
Daniel Bristot de Oliveira 632478a058 tracing/timerlat: Always wakeup the timerlat thread
While testing rtla timerlat auto analysis, I reach a condition where
the interface was not receiving tracing data. I was able to manually
reproduce the problem with these steps:

  # echo 0 > tracing_on                 # disable trace
  # echo 1 > osnoise/stop_tracing_us    # stop trace if timerlat irq > 1 us
  # echo timerlat > current_tracer      # enable timerlat tracer
  # sleep 1                             # wait... that is the time when rtla
                                        # apply configs like prio or cgroup
  # echo 1 > tracing_on                 # start tracing
  # cat trace
  # tracer: timerlat
  #
  #                                _-----=> irqs-off
  #                               / _----=> need-resched
  #                              | / _---=> hardirq/softirq
  #                              || / _--=> preempt-depth
  #                              ||| / _-=> migrate-disable
  #                              |||| /     delay
  #                              |||||            ACTIVATION
  #           TASK-PID      CPU# |||||   TIMESTAMP   ID            CONTEXT                 LATENCY
  #              | |         |   |||||      |         |                  |                       |
        NOTHING!

Then, trying to enable tracing again with echo 1 > tracing_on resulted
in no change: the trace was still not tracing.

This problem happens because the timerlat IRQ hits the stop tracing
condition while tracing is off, and do not wake up the timerlat thread,
so the timerlat threads are kept sleeping forever, resulting in no
trace, even after re-enabling the tracer.

Avoid this condition by always waking up the threads, even after stopping
tracing, allowing the tracer to return to its normal operating after
a new tracing on.

Link: https://lore.kernel.org/linux-trace-kernel/1ed8f830638b20a39d535d27d908e319a9a3c4e2.1683822622.git.bristot@kernel.org

Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: stable@vger.kernel.org
Fixes: a955d7eac1 ("trace: Add timerlat tracer")
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-23 11:54:31 -04:00
Beau Belgrave ee7751b564 tracing/user_events: Use long vs int for atomic bit ops
Each event stores a int to track which bit to set/clear when enablement
changes. On big endian 64-bit configurations, it's possible this could
cause memory corruption when it's used for atomic bit operations.

Use unsigned long for enablement values to ensure any possible
corruption cannot occur. Downcast to int after mask for the bit target.

Link: https://lore.kernel.org/all/6f758683-4e5e-41c3-9b05-9efc703e827c@kili.mountain/
Link: https://lore.kernel.org/linux-trace-kernel/20230505205855.6407-1-beaub@linux.microsoft.com

Fixes: dcb8177c13 ("tracing/user_events: Add ioctl for disabling addresses")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-23 10:40:34 -04:00
Harshit Mogalapalli d36f6efbe0 module: Fix use-after-free bug in read_file_mod_stats()
Smatch warns:
	kernel/module/stats.c:394 read_file_mod_stats()
	warn: passing freed memory 'buf'

We are passing 'buf' to simple_read_from_buffer() after freeing it.

Fix this by changing the order of 'simple_read_from_buffer' and 'kfree'.

Fixes: df3e764d8e ("module: add debug stats to help identify memory pressure")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2023-05-22 14:13:13 -07:00
Anton Protopopov b34ffb0c6d bpf: fix a memory leak in the LRU and LRU_PERCPU hash maps
The LRU and LRU_PERCPU maps allocate a new element on update before locking the
target hash table bucket. Right after that the maps try to lock the bucket.
If this fails, then maps return -EBUSY to the caller without releasing the
allocated element. This makes the element untracked: it doesn't belong to
either of free lists, and it doesn't belong to the hash table, so can't be
re-used; this eventually leads to the permanent -ENOMEM on LRU map updates,
which is unexpected. Fix this by returning the element to the local free list
if bucket locking fails.

Fixes: 20b6cc34ea ("bpf: Avoid hashtab deadlock with map_locked")
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Link: https://lore.kernel.org/r/20230522154558.2166815-1-aspsk@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2023-05-22 10:26:39 -07:00
Will Deacon 0613d8ca9a bpf: Fix mask generation for 32-bit narrow loads of 64-bit fields
A narrow load from a 64-bit context field results in a 64-bit load
followed potentially by a 64-bit right-shift and then a bitwise AND
operation to extract the relevant data.

In the case of a 32-bit access, an immediate mask of 0xffffffff is used
to construct a 64-bit BPP_AND operation which then sign-extends the mask
value and effectively acts as a glorified no-op. For example:

0:	61 10 00 00 00 00 00 00	r0 = *(u32 *)(r1 + 0)

results in the following code generation for a 64-bit field:

	ldr	x7, [x7]	// 64-bit load
	mov	x10, #0xffffffffffffffff
	and	x7, x7, x10

Fix the mask generation so that narrow loads always perform a 32-bit AND
operation:

	ldr	x7, [x7]	// 64-bit load
	mov	w10, #0xffffffff
	and	w7, w7, w10

Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Krzesimir Nowak <krzesimir@kinvolk.io>
Cc: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Fixes: 31fd85816d ("bpf: permits narrower load from bpf program context fields")
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230518102528.1341-1-will@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-05-19 09:58:37 -07:00
Linus Torvalds 2d1bcbc6cd Probes fixes for 6.4-rc1:
- Initialize 'ret' local variables on fprobe_handler() to fix the smatch
   warning. With this, fprobe function exit handler is not working
   randomly.
 
 - Fix to use preempt_enable/disable_notrace for rethook handler to
   prevent recursive call of fprobe exit handler (which is based on
   rethook)
 
 - Fix recursive call issue on fprobe_kprobe_handler().
 
 - Fix to detect recursive call on fprobe_exit_handler().
 
 - Fix to make all arch-dependent rethook code notrace.
   (the arch-independent code is already notrace)
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Merge tag 'probes-fixes-v6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull probes fixes from Masami Hiramatsu:

 - Initialize 'ret' local variables on fprobe_handler() to fix the
   smatch warning. With this, fprobe function exit handler is not
   working randomly.

 - Fix to use preempt_enable/disable_notrace for rethook handler to
   prevent recursive call of fprobe exit handler (which is based on
   rethook)

 - Fix recursive call issue on fprobe_kprobe_handler()

 - Fix to detect recursive call on fprobe_exit_handler()

 - Fix to make all arch-dependent rethook code notrace (the
   arch-independent code is already notrace)"

* tag 'probes-fixes-v6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  rethook, fprobe: do not trace rethook related functions
  fprobe: add recursion detection in fprobe_exit_handler
  fprobe: make fprobe_kprobe_handler recursion free
  rethook: use preempt_{disable, enable}_notrace in rethook_trampoline_handler
  tracing: fprobe: Initialize ret valiable to fix smatch error
2023-05-18 09:04:45 -07:00
Ze Gao 2752741080 fprobe: add recursion detection in fprobe_exit_handler
fprobe_hander and fprobe_kprobe_handler has guarded ftrace recursion
detection but fprobe_exit_handler has not, which possibly introduce
recursive calls if the fprobe exit callback calls any traceable
functions. Checking in fprobe_hander or fprobe_kprobe_handler
is not enough and misses this case.

So add recursion free guard the same way as fprobe_hander. Since
ftrace recursion check does not employ ip(s), so here use entry_ip and
entry_parent_ip the same as fprobe_handler.

Link: https://lore.kernel.org/all/20230517034510.15639-4-zegao@tencent.com/

Fixes: 5b0ab78998 ("fprobe: Add exit_handler support")
Signed-off-by: Ze Gao <zegao@tencent.com>
Cc: stable@vger.kernel.org
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
2023-05-18 07:08:01 +09:00
Ze Gao 3cc4e2c5fb fprobe: make fprobe_kprobe_handler recursion free
Current implementation calls kprobe related functions before doing
ftrace recursion check in fprobe_kprobe_handler, which opens door
to kernel crash due to stack recursion if preempt_count_{add, sub}
is traceable in kprobe_busy_{begin, end}.

Things goes like this without this patch quoted from Steven:
"
fprobe_kprobe_handler() {
   kprobe_busy_begin() {
      preempt_disable() {
         preempt_count_add() {  <-- trace
            fprobe_kprobe_handler() {
		[ wash, rinse, repeat, CRASH!!! ]
"

By refactoring the common part out of fprobe_kprobe_handler and
fprobe_handler and call ftrace recursion detection at the very beginning,
the whole fprobe_kprobe_handler is free from recursion.

[ Fix the indentation of __fprobe_handler() parameters. ]

Link: https://lore.kernel.org/all/20230517034510.15639-3-zegao@tencent.com/

Fixes: ab51e15d53 ("fprobe: Introduce FPROBE_FL_KPROBE_SHARED flag for fprobe")
Signed-off-by: Ze Gao <zegao@tencent.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
2023-05-18 07:08:01 +09:00
Ze Gao be243bacfb rethook: use preempt_{disable, enable}_notrace in rethook_trampoline_handler
This patch replaces preempt_{disable, enable} with its corresponding
notrace version in rethook_trampoline_handler so no worries about stack
recursion or overflow introduced by preempt_count_{add, sub} under
fprobe + rethook context.

Link: https://lore.kernel.org/all/20230517034510.15639-2-zegao@tencent.com/

Fixes: 54ecbe6f1e ("rethook: Add a generic return hook")
Signed-off-by: Ze Gao <zegao@tencent.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
2023-05-18 07:08:01 +09:00
Masami Hiramatsu (Google) 6049674b57 tracing: fprobe: Initialize ret valiable to fix smatch error
The commit 39d954200b ("fprobe: Skip exit_handler if entry_handler returns
!0") introduced a hidden dependency of 'ret' local variable in the
fprobe_handler(), Smatch warns the `ret` can be accessed without
initialization.

	kernel/trace/fprobe.c:59 fprobe_handler()
	error: uninitialized symbol 'ret'.

kernel/trace/fprobe.c
    49                 fpr->entry_ip = ip;
    50                 if (fp->entry_data_size)
    51                         entry_data = fpr->data;
    52         }
    53
    54         if (fp->entry_handler)
    55                 ret = fp->entry_handler(fp, ip, ftrace_get_regs(fregs), entry_data);

ret is only initialized if there is an ->entry_handler

    56
    57         /* If entry_handler returns !0, nmissed is not counted. */
    58         if (rh) {

rh is only true if there is an ->exit_handler.  Presumably if you have
and ->exit_handler that means you also have a ->entry_handler but Smatch
is not smart enough to figure it out.

--> 59                 if (ret)
                           ^^^
Warning here.

    60                         rethook_recycle(rh);
    61                 else
    62                         rethook_hook(rh, ftrace_get_regs(fregs), true);
    63         }
    64 out:
    65         ftrace_test_recursion_unlock(bit);
    66 }

Link: https://lore.kernel.org/all/168100731160.79534.374827110083836722.stgit@devnote2/

Reported-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/all/85429a5c-a4b9-499e-b6c0-cbd313291c49@kili.mountain
Fixes: 39d954200b ("fprobe: Skip exit_handler if entry_handler returns !0")
Acked-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
2023-05-17 20:42:59 +09:00
Jakub Kicinski e1505c1cc8 bpf: netdev: init the offload table earlier
Some netdevices may get unregistered before late_initcall(),
we have to move the hashtable init earlier.

Fixes: f1fc43d039 ("bpf: Move offload initialization into late_initcall")
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217399
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230505215836.491485-1-kuba@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-05-15 07:07:41 -07:00
Linus Torvalds 31f4104e39 - Make sure __down_read_common() is always inlined so that the callers'
names land in traceevents output instead and thus the blocked function
   can be identified
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Merge tag 'locking_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking fix from Borislav Petkov:

 - Make sure __down_read_common() is always inlined so that the callers'
   names land in traceevents output and thus the blocked function can be
   identified

* tag 'locking_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/rwsem: Add __always_inline annotation to __down_read_common() and inlined callers
2023-05-14 08:00:46 -07:00
Linus Torvalds ef21831c2e - Make sure the PEBS buffer is flushed before reprogramming the hardware
so that the correct record sizes are used
 
 - Update the sample size for AMD BRS events
 
 - Fix a confusion with using the same on-stack struct with different
   events in the event processing path
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Merge tag 'perf_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fixes from Borislav Petkov:

 - Make sure the PEBS buffer is flushed before reprogramming the
   hardware so that the correct record sizes are used

 - Update the sample size for AMD BRS events

 - Fix a confusion with using the same on-stack struct with different
   events in the event processing path

* tag 'perf_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel/ds: Flush PEBS DS when changing PEBS_DATA_CFG
  perf/x86: Fix missing sample size update on AMD BRS
  perf/core: Fix perf_sample_data not properly initialized for different swevents in perf_tp_event()
2023-05-14 07:56:51 -07:00
Linus Torvalds f3b9e8e4c8 - Fix a couple of kernel-doc warnings
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Merge tag 'sched_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fix from Borislav Petkov:

 - Fix a couple of kernel-doc warnings

* tag 'sched_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: fix cid_lock kernel-doc warnings
2023-05-14 07:50:34 -07:00
Thomas Gleixner f9d36cf445 tick/broadcast: Make broadcast device replacement work correctly
When a tick broadcast clockevent device is initialized for one shot mode
then tick_broadcast_setup_oneshot() OR's the periodic broadcast mode
cpumask into the oneshot broadcast cpumask.

This is required when switching from periodic broadcast mode to oneshot
broadcast mode to ensure that CPUs which are waiting for periodic
broadcast are woken up on the next tick.

But it is subtly broken, when an active broadcast device is replaced and
the system is already in oneshot (NOHZ/HIGHRES) mode. Victor observed
this and debugged the issue.

Then the OR of the periodic broadcast CPU mask is wrong as the periodic
cpumask bits are sticky after tick_broadcast_enable() set it for a CPU
unless explicitly cleared via tick_broadcast_disable().

That means that this sets all other CPUs which have tick broadcasting
enabled at that point unconditionally in the oneshot broadcast mask.

If the affected CPUs were already idle and had their bits set in the
oneshot broadcast mask then this does no harm. But for non idle CPUs
which were not set this corrupts their state.

On their next invocation of tick_broadcast_enable() they observe the bit
set, which indicates that the broadcast for the CPU is already set up.
As a consequence they fail to update the broadcast event even if their
earliest expiring timer is before the actually programmed broadcast
event.

If the programmed broadcast event is far in the future, then this can
cause stalls or trigger the hung task detector.

Avoid this by telling tick_broadcast_setup_oneshot() explicitly whether
this is the initial switch over from periodic to oneshot broadcast which
must take the periodic broadcast mask into account. In the case of
initialization of a replacement device this prevents that the broadcast
oneshot mask is modified.

There is a second problem with broadcast device replacement in this
function. The broadcast device is only armed when the previous state of
the device was periodic.

That is correct for the switch from periodic broadcast mode to oneshot
broadcast mode as the underlying broadcast device could operate in
oneshot state already due to lack of periodic state in hardware. In that
case it is already armed to expire at the next tick.

For the replacement case this is wrong as the device is in shutdown
state. That means that any already pending broadcast event will not be
armed.

This went unnoticed because any CPU which goes idle will observe that
the broadcast device has an expiry time of KTIME_MAX and therefore any
CPUs next timer event will be earlier and cause a reprogramming of the
broadcast device. But that does not guarantee that the events of the
CPUs which were already in idle are delivered on time.

Fix this by arming the newly installed device for an immediate event
which will reevaluate the per CPU expiry times and reprogram the
broadcast device accordingly. This is simpler than caching the last
expiry time in yet another place or saving it before the device exchange
and handing it down to the setup function. Replacement of broadcast
devices is not a frequent operation and usually happens once somewhere
late in the boot process.

Fixes: 9c336c9935 ("tick/broadcast: Allow late registered device to enter oneshot mode")
Reported-by: Victor Hassan <victor@allwinnertech.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/87pm7d2z1i.ffs@tglx
2023-05-08 23:18:16 +02:00
Randy Dunlap 0019a2d4b7 sched: fix cid_lock kernel-doc warnings
Fix kernel-doc warnings for cid_lock and use_cid_lock.
These comments are not in kernel-doc format.

kernel/sched/core.c:11496: warning: Cannot understand  * @cid_lock: Guarantee forward-progress of cid allocation.
 on line 11496 - I thought it was a doc line
kernel/sched/core.c:11505: warning: Cannot understand  * @use_cid_lock: Select cid allocation behavior: lock-free vs spinlock.
 on line 11505 - I thought it was a doc line

Fixes: 223baf9d17 ("sched: Fix performance regression introduced by mm_cid")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230428031111.322-1-rdunlap@infradead.org
2023-05-08 10:58:28 +02:00
Yang Jihong 1d1bfe30da perf/core: Fix perf_sample_data not properly initialized for different swevents in perf_tp_event()
data->sample_flags may be modified in perf_prepare_sample(),
in perf_tp_event(), different swevents use the same on-stack
perf_sample_data, the previous swevent may change sample_flags in
perf_prepare_sample(), as a result, some members of perf_sample_data are
not correctly initialized when next swevent_event preparing sample
(for example data->id, the value varies according to swevent).

A simple scenario triggers this problem is as follows:

  # perf record -e sched:sched_switch --switch-output-event sched:sched_switch -a sleep 1
  [ perf record: dump data: Woken up 0 times ]
  [ perf record: Dump perf.data.2023041209014396 ]
  [ perf record: dump data: Woken up 0 times ]
  [ perf record: Dump perf.data.2023041209014662 ]
  [ perf record: dump data: Woken up 0 times ]
  [ perf record: Dump perf.data.2023041209014910 ]
  [ perf record: Woken up 0 times to write data ]
  [ perf record: Dump perf.data.2023041209015164 ]
  [ perf record: Captured and wrote 0.069 MB perf.data.<timestamp> ]
  # ls -l
  total 860
  -rw------- 1 root root  95694 Apr 12 09:01 perf.data.2023041209014396
  -rw------- 1 root root 606430 Apr 12 09:01 perf.data.2023041209014662
  -rw------- 1 root root  82246 Apr 12 09:01 perf.data.2023041209014910
  -rw------- 1 root root  82342 Apr 12 09:01 perf.data.2023041209015164
  # perf script -i perf.data.2023041209014396
  0x11d58 [0x80]: failed to process type: 9 [Bad address]

Solution: Re-initialize perf_sample_data after each event is processed.
Note that data->raw->frag.data may be accessed in perf_tp_event_match().
Therefore, need to init sample_data and then go through swevent hlist to prevent
reference of NULL pointer, reported by [1].

After fix:

  # perf record -e sched:sched_switch --switch-output-event sched:sched_switch -a sleep 1
  [ perf record: dump data: Woken up 0 times ]
  [ perf record: Dump perf.data.2023041209442259 ]
  [ perf record: dump data: Woken up 0 times ]
  [ perf record: Dump perf.data.2023041209442514 ]
  [ perf record: dump data: Woken up 0 times ]
  [ perf record: Dump perf.data.2023041209442760 ]
  [ perf record: Woken up 0 times to write data ]
  [ perf record: Dump perf.data.2023041209443003 ]
  [ perf record: Captured and wrote 0.069 MB perf.data.<timestamp> ]
  # ls -l
  total 864
  -rw------- 1 root root 100166 Apr 12 09:44 perf.data.2023041209442259
  -rw------- 1 root root 606438 Apr 12 09:44 perf.data.2023041209442514
  -rw------- 1 root root  82246 Apr 12 09:44 perf.data.2023041209442760
  -rw------- 1 root root  82342 Apr 12 09:44 perf.data.2023041209443003
  # perf script -i perf.data.2023041209442259 | head -n 5
              perf   232 [000]    66.846217: sched:sched_switch: prev_comm=perf prev_pid=232 prev_prio=120 prev_state=D ==> next_comm=perf next_pid=234 next_prio=120
              perf   234 [000]    66.846449: sched:sched_switch: prev_comm=perf prev_pid=234 prev_prio=120 prev_state=S ==> next_comm=perf next_pid=232 next_prio=120
              perf   232 [000]    66.846546: sched:sched_switch: prev_comm=perf prev_pid=232 prev_prio=120 prev_state=R ==> next_comm=perf next_pid=234 next_prio=120
              perf   234 [000]    66.846606: sched:sched_switch: prev_comm=perf prev_pid=234 prev_prio=120 prev_state=S ==> next_comm=perf next_pid=232 next_prio=120
              perf   232 [000]    66.846646: sched:sched_switch: prev_comm=perf prev_pid=232 prev_prio=120 prev_state=R ==> next_comm=perf next_pid=234 next_prio=120

[1] Link: https://lore.kernel.org/oe-lkp/202304250929.efef2caa-yujie.liu@intel.com

Fixes: bb447c27a4 ("perf/core: Set data->sample_flags in perf_prepare_sample()")
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230425103217.130600-1-yangjihong1@huawei.com
2023-05-08 10:58:26 +02:00
John Stultz 92cc5d00a4 locking/rwsem: Add __always_inline annotation to __down_read_common() and inlined callers
Apparently despite it being marked inline, the compiler
may not inline __down_read_common() which makes it difficult
to identify the cause of lock contention, as the blocked
function in traceevents will always be listed as
__down_read_common().

So this patch adds __always_inline annotation to the common
function (as well as the inlined helper callers) to force it to
be inlined so the blocking function will be listed (via Wchan)
in traceevents.

Fixes: c995e638cc ("locking/rwsem: Fold __down_{read,write}*()")
Reported-by: Tim Murray <timmurray@google.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20230503023351.2832796-1-jstultz@google.com
2023-05-08 10:58:24 +02:00
Linus Torvalds e919a3f705 Minor tracing updates:
- Make buffer_percent read/write. The buffer_percent file is how users can
   state how long to block on the tracing buffer depending on how much
   is in the buffer. When it hits the "buffer_percent" it will wake the
   task waiting on the buffer. For some reason it was set to read-only.
   This was not noticed because testing was done as root without SELinux,
   but with SELinux it will prevent even root to write to it without having
   CAP_DAC_OVERRIDE.
 
 - The "touched_functions" was added this merge window, but one of the
   reasons for adding it was not implemented. That was to show what functions
   were not only touched, but had either a direct trampoline attached to
   it, or a kprobe or live kernel patching that can "hijack" the function
   to run a different function. The point is to know if there's functions
   in the kernel that may not be behaving as the kernel code shows. This can
   be used for debugging. TODO: Add this information to kernel oops too.
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Merge tag 'trace-v6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull more tracing updates from Steven Rostedt:

 - Make buffer_percent read/write.

   The buffer_percent file is how users can state how long to block on
   the tracing buffer depending on how much is in the buffer. When it
   hits the "buffer_percent" it will wake the task waiting on the
   buffer. For some reason it was set to read-only.

   This was not noticed because testing was done as root without
   SELinux, but with SELinux it will prevent even root to write to it
   without having CAP_DAC_OVERRIDE.

 - The "touched_functions" was added this merge window, but one of the
   reasons for adding it was not implemented.

   That was to show what functions were not only touched, but had either
   a direct trampoline attached to it, or a kprobe or live kernel
   patching that can "hijack" the function to run a different function.
   The point is to know if there's functions in the kernel that may not
   be behaving as the kernel code shows. This can be used for debugging.

   TODO: Add this information to kernel oops too.

* tag 'trace-v6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ftrace: Add MODIFIED flag to show if IPMODIFY or direct was attached
  tracing: Fix permissions for the buffer_percent file
2023-05-05 13:11:02 -07:00
Linus Torvalds b115d85a95 Locking changes in v6.4:
- Introduce local{,64}_try_cmpxchg() - a slightly more optimal
    primitive, which will be used in perf events ring-buffer code.
 
  - Simplify/modify rwsems on PREEMPT_RT, to address writer starvation.
 
  - Misc cleanups/fixes.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2023-05-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:

 - Introduce local{,64}_try_cmpxchg() - a slightly more optimal
   primitive, which will be used in perf events ring-buffer code

 - Simplify/modify rwsems on PREEMPT_RT, to address writer starvation

 - Misc cleanups/fixes

* tag 'locking-core-2023-05-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/atomic: Correct (cmp)xchg() instrumentation
  locking/x86: Define arch_try_cmpxchg_local()
  locking/arch: Wire up local_try_cmpxchg()
  locking/generic: Wire up local{,64}_try_cmpxchg()
  locking/atomic: Add generic try_cmpxchg{,64}_local() support
  locking/rwbase: Mitigate indefinite writer starvation
  locking/arch: Rename all internal __xchg() names to __arch_xchg()
2023-05-05 12:56:55 -07:00
Steven Rostedt (Google) 6ce2c04fcb ftrace: Add MODIFIED flag to show if IPMODIFY or direct was attached
If a function had ever had IPMODIFY or DIRECT attached to it, where this
is how live kernel patching and BPF overrides work, mark them and display
an "M" in the enabled_functions and touched_functions files. This can be
used for debugging. If a function had been modified and later there's a bug
in the code related to that function, this can be used to know if the cause
is possibly from a live kernel patch or a BPF program that changed the
behavior of the code.

Also update the documentation on the enabled_functions and
touched_functions output, as it was missing direct callers and CALL_OPS.
And include this new modify attribute.

Link: https://lore.kernel.org/linux-trace-kernel/20230502213233.004e3ae4@gandalf.local.home

Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-05 11:09:25 -04:00
Linus Torvalds a1fd058b07 Five hotfixes. Three are cc:stable, two for this -rc cycle.
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Merge tag 'mm-hotfixes-stable-2023-05-03-16-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull hitfixes from Andrew Morton:
 "Five hotfixes.  Three are cc:stable, two for this -rc cycle"

* tag 'mm-hotfixes-stable-2023-05-03-16-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  mm: change per-VMA lock statistics to be disabled by default
  MAINTAINERS: update Michal Simek's email
  mm/mempolicy: correctly update prev when policy is equal on mbind
  relayfs: fix out-of-bounds access in relay_file_read
  kasan: hw_tags: avoid invalid virt_to_page()
2023-05-04 13:21:16 -07:00
Linus Torvalds 15fb96a35d - Some DAMON cleanups from Kefeng Wang
- Some KSM work from David Hildenbrand, to make the PR_SET_MEMORY_MERGE
   ioctl's behavior more similar to KSM's behavior.
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Merge tag 'mm-stable-2023-05-03-16-22' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull more MM updates from Andrew Morton:

 - Some DAMON cleanups from Kefeng Wang

 - Some KSM work from David Hildenbrand, to make the PR_SET_MEMORY_MERGE
   ioctl's behavior more similar to KSM's behavior.

[ Andrew called these "final", but I suspect we'll have a series fixing
  up the fact that the last commit in the dmapools series in the
  previous pull seems to have unintentionally just reverted all the
  other commits in the same series..   - Linus ]

* tag 'mm-stable-2023-05-03-16-22' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  mm: hwpoison: coredump: support recovery from dump_user_range()
  mm/page_alloc: add some comments to explain the possible hole in __pageblock_pfn_to_page()
  mm/ksm: move disabling KSM from s390/gmap code to KSM code
  selftests/ksm: ksm_functional_tests: add prctl unmerge test
  mm/ksm: unmerge and clear VM_MERGEABLE when setting PR_SET_MEMORY_MERGE=0
  mm/damon/paddr: fix missing folio_sz update in damon_pa_young()
  mm/damon/paddr: minor refactor of damon_pa_mark_accessed_or_deactivate()
  mm/damon/paddr: minor refactor of damon_pa_pageout()
2023-05-04 13:09:43 -07:00
Linus Torvalds b408242872 modules-6.4-rc1 v2
There is only one fix by Arnd far for modules pending which came in after
 the first pull request. The issue was found as part of some late compile
 tests with 0-day. I take it 0-day does some secondary late builds with
 after some initial ones.
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Merge tag 'modules-6.4-rc1-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

Pull modules fix from Luis Chamberlain:
 "One fix by Arnd far for modules which came in after the first pull
  request.

  The issue was found as part of some late compile tests with 0-day. I
  take it 0-day does some secondary late builds with after some initial
  ones"

* tag 'modules-6.4-rc1-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
  module: include internal.h in module/dups.c
2023-05-03 19:19:34 -07:00
Linus Torvalds 049a18f232 sysctl-6.4-rc1-v2
As mentioned on my first pull request for sysctl-next, for v6.4-rc1
 we're very close to being able to deprecating register_sysctl_paths().
 I was going to assess the situation after the first week of the merge
 window.
 
 That time is now and things are looking good. We only have one stragglers
 on the patch which had already an ACK for so I'm picking this up here now and
 the last patch is the one that uses an axe. Some careful eyeballing would
 be appreciated by others. If this doesn't get properly reviewed I can also
 just hold off on this in my tree for the next merge window. Either way is
 fine by me.
 
 I have boot tested the last patch and 0-day build completed successfully.
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Merge tag 'sysctl-6.4-rc1-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

Pull more sysctl updates from Luis Chamberlain:
 "As mentioned on my first pull request for sysctl-next, for v6.4-rc1
  we're very close to being able to deprecating register_sysctl_paths().
  I was going to assess the situation after the first week of the merge
  window.

  That time is now and things are looking good. We only have one which
  had already an ACK for so I'm picking this up here now and the last
  patch is the one that uses an axe.

  I have boot tested the last patch and 0-day build completed
  successfully"

* tag 'sysctl-6.4-rc1-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
  sysctl: remove register_sysctl_paths()
  kernel: pid_namespace: simplify sysctls with register_sysctl()
2023-05-03 19:08:20 -07:00
Linus Torvalds fa31fc82fb More power management updates for 6.4-rc1
- Make test_resume work again after the changes that made hibernation
    open the snapshot device in exclusive mode (Chen Yu).
 
  - Clean up code in several places in intel_idle (Artem Bityutskiy).
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Merge tag 'pm-6.4-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull more power management updates from Rafael Wysocki:
 "These fix a hibernation test mode regression and clean up the
  intel_idle driver.

  Specifics:

   - Make test_resume work again after the changes that made hibernation
     open the snapshot device in exclusive mode (Chen Yu)

   - Clean up code in several places in intel_idle (Artem Bityutskiy)"

* tag 'pm-6.4-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  intel_idle: mark few variables as __read_mostly
  intel_idle: do not sprinkle module parameter definitions around
  intel_idle: fix confusing message
  intel_idle: improve C-state flags handling robustness
  intel_idle: further intel_idle_init_cstates_icpu() cleanup
  intel_idle: clean up intel_idle_init_cstates_icpu()
  intel_idle: use pr_info() instead of printk()
  PM: hibernate: Do not get block device exclusively in test_resume mode
  PM: hibernate: Turn snapshot_test into global variable
2023-05-03 12:01:05 -07:00
Ondrej Mosnacek 4f94559f40 tracing: Fix permissions for the buffer_percent file
This file defines both read and write operations, yet it is being
created as read-only. This means that it can't be written to without the
CAP_DAC_OVERRIDE capability. Fix the permissions to allow root to write
to it without the need to override DAC perms.

Link: https://lore.kernel.org/linux-trace-kernel/20230503140114.3280002-1-omosnace@redhat.com

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: 03329f9939 ("tracing: Add tracefs file buffer_percentage")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-03 12:45:00 -04:00
Arnd Bergmann 0b891c83d8 module: include internal.h in module/dups.c
Two newly introduced functions are declared in a header that is not
included before the definition, causing a warning with sparse or
'make W=1':

kernel/module/dups.c:118:6: error: no previous prototype for 'kmod_dup_request_exists_wait' [-Werror=missing-prototypes]
  118 | bool kmod_dup_request_exists_wait(char *module_name, bool wait, int *dup_ret)
      |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/module/dups.c:220:6: error: no previous prototype for 'kmod_dup_request_announce' [-Werror=missing-prototypes]
  220 | void kmod_dup_request_announce(char *module_name, int ret)
      |      ^~~~~~~~~~~~~~~~~~~~~~~~~

Add an explicit include to ensure the prototypes match.

Fixes: 8660484ed1 ("module: add debugging auto-load duplicate module support")
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202304141440.DYO4NAzp-lkp@intel.com/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2023-05-02 20:33:36 -07:00
Luis Chamberlain 9e7c73c0b9 kernel: pid_namespace: simplify sysctls with register_sysctl()
register_sysctl_paths() is only required if your child (directories)
have entries and pid_namespace does not. So use register_sysctl_init()
instead where we don't care about the return value and use
register_sysctl() where we do.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Jeff Xu <jeffxu@google.com>
Link: https://lore.kernel.org/r/20230302202826.776286-9-mcgrof@kernel.org
2023-05-02 19:23:29 -07:00
Zhang Zhengming 43ec16f145 relayfs: fix out-of-bounds access in relay_file_read
There is a crash in relay_file_read, as the var from
point to the end of last subbuf.

The oops looks something like:
pc : __arch_copy_to_user+0x180/0x310
lr : relay_file_read+0x20c/0x2c8
Call trace:
 __arch_copy_to_user+0x180/0x310
 full_proxy_read+0x68/0x98
 vfs_read+0xb0/0x1d0
 ksys_read+0x6c/0xf0
 __arm64_sys_read+0x20/0x28
 el0_svc_common.constprop.3+0x84/0x108
 do_el0_svc+0x74/0x90
 el0_svc+0x1c/0x28
 el0_sync_handler+0x88/0xb0
 el0_sync+0x148/0x180

We get the condition by analyzing the vmcore:

1). The last produced byte and last consumed byte
    both at the end of the last subbuf

2). A softirq calls function(e.g __blk_add_trace)
    to write relay buffer occurs when an program is calling
    relay_file_read_avail().

        relay_file_read
                relay_file_read_avail
                        relay_file_read_consume(buf, 0, 0);
                        //interrupted by softirq who will write subbuf
                        ....
                        return 1;
                //read_start point to the end of the last subbuf
                read_start = relay_file_read_start_pos
                //avail is equal to subsize
                avail = relay_file_read_subbuf_avail
                //from  points to an invalid memory address
                from = buf->start + read_start
                //system is crashed
                copy_to_user(buffer, from, avail)

Link: https://lkml.kernel.org/r/20230419040203.37676-1-zhang.zhengming@h3c.com
Fixes: 8d62fdebda ("relay file read: start-pos fix")
Signed-off-by: Zhang Zhengming <zhang.zhengming@h3c.com>
Reviewed-by: Zhao Lei <zhao_lei1@hoperun.com>
Reviewed-by: Zhou Kete <zhou.kete@h3c.com>
Reviewed-by: Pengcheng Yang <yangpc@wangsu.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-05-02 17:23:27 -07:00
David Hildenbrand 24139c07f4 mm/ksm: unmerge and clear VM_MERGEABLE when setting PR_SET_MEMORY_MERGE=0
Patch series "mm/ksm: improve PR_SET_MEMORY_MERGE=0 handling and cleanup
disabling KSM", v2.

(1) Make PR_SET_MEMORY_MERGE=0 unmerge pages like setting MADV_UNMERGEABLE
does, (2) add a selftest for it and (3) factor out disabling of KSM from
s390/gmap code.


This patch (of 3):

Let's unmerge any KSM pages when setting PR_SET_MEMORY_MERGE=0, and clear
the VM_MERGEABLE flag from all VMAs -- just like KSM would.  Of course,
only do that if we previously set PR_SET_MEMORY_MERGE=1.

Link: https://lkml.kernel.org/r/20230422205420.30372-1-david@redhat.com
Link: https://lkml.kernel.org/r/20230422205420.30372-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Stefan Roesch <shr@devkernel.io>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-05-02 17:21:49 -07:00