linux-stable.git/Documentation/admin-guide, branch v6.1.78

docs: kernel_abi.py: fix command injection

2024-02-01T00:17:00+00:00

commit 3231dd5862779c2e15633c96133a53205ad660ce upstream.

The kernel-abi directive passes its argument straight to the shell.
This is unfortunate and unnecessary.

Let's always use paths relative to $srctree/Documentation/ and use
subprocess.check_call() instead of subprocess.Popen(shell=True).

This also makes the code shorter.

Link: https://fosstodon.org/@jani/111676532203641247
Reported-by: Jani Nikula 
Cc: stable@vger.kernel.org
Signed-off-by: Vegard Nossum 
Signed-off-by: Jonathan Corbet 
Link: https://lore.kernel.org/r/20231231235959.3342928-2-vegard.nossum@oracle.com
Signed-off-by: Greg Kroah-Hartman

smp,csd: Throw an error if a CSD lock is stuck for too long

2023-11-28T17:06:55+00:00

[ Upstream commit 94b3f0b5af2c7af69e3d6e0cdd9b0ea535f22186 ]

The CSD lock seems to get stuck in 2 "modes". When it gets stuck
temporarily, it usually gets released in a few seconds, and sometimes
up to one or two minutes.

If the CSD lock stays stuck for more than several minutes, it never
seems to get unstuck, and gradually more and more things in the system
end up also getting stuck.

In the latter case, we should just give up, so the system can dump out
a little more information about what went wrong, and, with panic_on_oops
and a kdump kernel loaded, dump a whole bunch more information about what
might have gone wrong.  In addition, there is an smp.panic_on_ipistall
kernel boot parameter that by default retains the old behavior, but when
set enables the panic after the CSD lock has been stuck for more than
the specified number of milliseconds, as in 300,000 for five minutes.

[ paulmck: Apply Imran Khan feedback. ]
[ paulmck: Apply Leonardo Bras feedback. ]

Link: https://lore.kernel.org/lkml/bc7cc8b0-f587-4451-8bcd-0daae627bcc7@paulmck-laptop/
Signed-off-by: Rik van Riel 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Imran Khan 
Reviewed-by: Leonardo Bras 
Cc: Peter Zijlstra 
Cc: Valentin Schneider 
Cc: Juergen Gross 
Cc: Jonathan Corbet 
Cc: Randy Dunlap 
Signed-off-by: Sasha Levin

mm, memcg: reconsider kmem.limit_in_bytes deprecation

2023-10-06T12:57:06+00:00

commit 4597648fddeadef5877610d693af11906aa666ac upstream.

This reverts commits 86327e8eb94c ("memcg: drop kmem.limit_in_bytes") and
partially reverts 58056f77502f ("memcg, kmem: further deprecate
kmem.limit_in_bytes") which have incrementally removed support for the
kernel memory accounting hard limit.  Unfortunately it has turned out that
there is still userspace depending on the existence of
memory.kmem.limit_in_bytes [1].  The underlying functionality is not
really required but the non-existent file just confuses the userspace
which fails in the result.  The patch to fix this on the userspace side
has been submitted but it is hard to predict how it will propagate through
the maze of 3rd party consumers of the software.

Now, reverting alone 86327e8eb94c is not an option because there is
another set of userspace which cannot cope with ENOTSUPP returned when
writing to the file.  Therefore we have to go and revisit 58056f77502f as
well.  There are two ways to go ahead.  Either we give up on the
deprecation and fully revert 58056f77502f as well or we can keep
kmem.limit_in_bytes but make the write a noop and warn about the fact.
This should work for both known breaking workloads which depend on the
existence but do not depend on the hard limit enforcement.

Note to backporters to stable trees.  a8c49af3be5f ("memcg: add per-memcg
total kernel memory stat") introduced in 4.18 has added memcg_account_kmem
so the accounting is not done by obj_cgroup_charge_pages directly for v1
anymore.  Prior kernels need to add it explicitly (thanks to Johannes for
pointing this out).

[akpm@linux-foundation.org: fix build - remove unused local]
Link: http://lkml.kernel.org/r/20230920081101.GA12096@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net [1]
Link: https://lkml.kernel.org/r/ZRE5VJozPZt9bRPy@dhcp22.suse.cz
Fixes: 86327e8eb94c ("memcg: drop kmem.limit_in_bytes")
Fixes: 58056f77502f ("memcg, kmem: further deprecate kmem.limit_in_bytes")
Signed-off-by: Michal Hocko 
Acked-by: Shakeel Butt 
Acked-by: Johannes Weiner 
Cc: Greg Kroah-Hartman 
Cc: Jeremi Piotrowski 
Cc: Muchun Song 
Cc: Roman Gushchin 
Cc: Tejun heo 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

memcg: drop kmem.limit_in_bytes

2023-10-06T12:57:06+00:00

commit 86327e8eb94c52eca4f93cfece2e29d1bf52acbf upstream.

kmem.limit_in_bytes (v1 way to limit kernel memory usage) has been
deprecated since 58056f77502f ("memcg, kmem: further deprecate
kmem.limit_in_bytes") merged in 5.16.  We haven't heard about any serious
users since then but it seems that the mere presence of the file is
causing more harm thatn good.  We (SUSE) have had several bug reports from
customers where Docker based containers started to fail because a write to
kmem.limit_in_bytes has failed.

This was unexpected because runc code only expects ENOENT (kmem disabled)
or EBUSY (tasks already running within cgroup).  So a new error code was
unexpected and the whole container startup failed.  This has been later
addressed by
https://github.com/opencontainers/runc/commit/52390d68040637dfc77f9fda6bbe70952423d380
so current Docker runtimes do not suffer from the problem anymore.  There
are still older version of Docker in use and likely hard to get rid of
completely.

Address this by wiping out the file completely and effectively get back to
pre 4.5 era and CONFIG_MEMCG_KMEM=n configuration.

I would recommend backporting to stable trees which have picked up
58056f77502f ("memcg, kmem: further deprecate kmem.limit_in_bytes").

[mhocko@suse.com: restore _KMEM switch case]
  Link: https://lkml.kernel.org/r/ZKe5wxdbvPi5Cwd7@dhcp22.suse.cz
Link: https://lkml.kernel.org/r/20230704115240.14672-1-mhocko@kernel.org
Signed-off-by: Michal Hocko 
Acked-by: Shakeel Butt 
Acked-by: Johannes Weiner 
Acked-by: Roman Gushchin 
Cc: Muchun Song 
Cc: Tejun Heo 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

Revert "memcg: drop kmem.limit_in_bytes"

2023-09-23T09:11:12+00:00

This reverts commit 21ef9e11205fca43785eecf7d4a99528d4de5701 which is
commit 86327e8eb94c52eca4f93cfece2e29d1bf52acbf upstream.

It breaks existing runc systems, as the tool always thinks the file
should be present.

Reported-by: Jeremi Piotrowski 
Link: https://lore.kernel.org/r/20230920081101.GA12096@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net
Cc: Michal Hocko 
Cc: Shakeel Butt 
Cc: Johannes Weiner 
Cc: Roman Gushchin 
Cc: Muchun Song 
Cc: Tejun Heo 
Cc: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

memcg: drop kmem.limit_in_bytes

2023-09-19T10:27:56+00:00

commit 86327e8eb94c52eca4f93cfece2e29d1bf52acbf upstream.

kmem.limit_in_bytes (v1 way to limit kernel memory usage) has been
deprecated since 58056f77502f ("memcg, kmem: further deprecate
kmem.limit_in_bytes") merged in 5.16.  We haven't heard about any serious
users since then but it seems that the mere presence of the file is
causing more harm thatn good.  We (SUSE) have had several bug reports from
customers where Docker based containers started to fail because a write to
kmem.limit_in_bytes has failed.

This was unexpected because runc code only expects ENOENT (kmem disabled)
or EBUSY (tasks already running within cgroup).  So a new error code was
unexpected and the whole container startup failed.  This has been later
addressed by
https://github.com/opencontainers/runc/commit/52390d68040637dfc77f9fda6bbe70952423d380
so current Docker runtimes do not suffer from the problem anymore.  There
are still older version of Docker in use and likely hard to get rid of
completely.

Address this by wiping out the file completely and effectively get back to
pre 4.5 era and CONFIG_MEMCG_KMEM=n configuration.

I would recommend backporting to stable trees which have picked up
58056f77502f ("memcg, kmem: further deprecate kmem.limit_in_bytes").

[mhocko@suse.com: restore _KMEM switch case]
  Link: https://lkml.kernel.org/r/ZKe5wxdbvPi5Cwd7@dhcp22.suse.cz
Link: https://lkml.kernel.org/r/20230704115240.14672-1-mhocko@kernel.org
Signed-off-by: Michal Hocko 
Acked-by: Shakeel Butt 
Acked-by: Johannes Weiner 
Acked-by: Roman Gushchin 
Cc: Muchun Song 
Cc: Tejun Heo 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

ACPI: thermal: Drop nocrt parameter

2023-09-02T07:16:18+00:00

commit 5f641174a12b8a876a4101201a21ef4675ecc014 upstream.

The `nocrt` module parameter has no code associated with it and does
nothing.  As `crt=-1` has same functionality as what nocrt should be
doing drop `nocrt` and associated documentation.

This should fix a quirk for Gigabyte GA-7ZX that used `nocrt` and
thus didn't function properly.

Fixes: 8c99fdce3078 ("ACPI: thermal: set "thermal.nocrt" via DMI on Gigabyte GA-7ZX")
Signed-off-by: Mario Limonciello 
Cc: All applicable 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

x86/cpu: Rename srso_(.*)_alias to srso_alias_\1

2023-08-26T11:26:59+00:00

commit 42be649dd1f2eee6b1fb185f1a231b9494cf095f upstream.

For a more consistent namespace.

  [ bp: Fixup names in the doc too. ]

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Borislav Petkov (AMD) 
Link: https://lore.kernel.org/r/20230814121148.976236447@infradead.org
Signed-off-by: Greg Kroah-Hartman

iommu/amd: Introduce Disable IRTE Caching Support

2023-08-23T15:52:21+00:00

[ Upstream commit 66419036f68a838c00cbccacd6cb2e99da6e5710 ]

An Interrupt Remapping Table (IRT) stores interrupt remapping configuration
for each device. In a normal operation, the AMD IOMMU caches the table
to optimize subsequent data accesses. This requires the IOMMU driver to
invalidate IRT whenever it updates the table. The invalidation process
includes issuing an INVALIDATE_INTERRUPT_TABLE command following by
a COMPLETION_WAIT command.

However, there are cases in which the IRT is updated at a high rate.
For example, for IOMMU AVIC, the IRTE[IsRun] bit is updated on every
vcpu scheduling (i.e. amd_iommu_update_ga()). On system with large
amount of vcpus and VFIO PCI pass-through devices, the invalidation
process could potentially become a performance bottleneck.

Introducing a new kernel boot option:

    amd_iommu=irtcachedis

which disables IRTE caching by setting the IRTCachedis bit in each IOMMU
Control register, and bypass the IRT invalidation process.

Reviewed-by: Jerry Snitselaar 
Co-developed-by: Alejandro Jimenez 
Signed-off-by: Alejandro Jimenez 
Signed-off-by: Suravee Suthikulpanit 
Link: https://lore.kernel.org/r/20230530141137.14376-4-suravee.suthikulpanit@amd.com
Signed-off-by: Joerg Roedel 
Signed-off-by: Sasha Levin

x86/srso: Add a Speculative RAS Overflow mitigation

2023-08-08T18:03:50+00:00

Upstream commit: fb3bd914b3ec28f5fb697ac55c4846ac2d542855

Add a mitigation for the speculative return address stack overflow
vulnerability found on AMD processors.

The mitigation works by ensuring all RET instructions speculate to
a controlled location, similar to how speculation is controlled in the
retpoline sequence.  To accomplish this, the __x86_return_thunk forces
the CPU to mispredict every function return using a 'safe return'
sequence.

To ensure the safety of this mitigation, the kernel must ensure that the
safe return sequence is itself free from attacker interference.  In Zen3
and Zen4, this is accomplished by creating a BTB alias between the
untraining function srso_untrain_ret_alias() and the safe return
function srso_safe_ret_alias() which results in evicting a potentially
poisoned BTB entry and using that safe one for all function returns.

In older Zen1 and Zen2, this is accomplished using a reinterpretation
technique similar to Retbleed one: srso_untrain_ret() and
srso_safe_ret().

Signed-off-by: Borislav Petkov (AMD) 
Signed-off-by: Greg Kroah-Hartman