Skip to content

L
linux
Switch branch/tag
  1. 03 Sep, 2020 34 commits
  3. 26 Aug, 2020 6 commits
    • Greg Kroah-Hartman's avatar
      Linux 4.19.142 · f6d5cb9e
      Greg Kroah-Hartman authored 
      Tested-by: default avatarJon Hunter <jonathanh@nvidia.com>
Tested-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      f6d5cb9e
    • Will Deacon's avatar
      KVM: arm64: Only reschedule if MMU_NOTIFIER_RANGE_BLOCKABLE is not set · 0f090712
      Will Deacon authored 
      commit b5331379 upstream.

When an MMU notifier call results in unmapping a range that spans multiple
PGDs, we end up calling into cond_resched_lock() when crossing a PGD boundary,
since this avoids running into RCU stalls during VM teardown. Unfortunately,
if the VM is destroyed as a result of OOM, then blocking is not permitted
and the call to the scheduler triggers the following BUG():

 | BUG: sleeping function called from invalid context at arch/arm64/kvm/mmu.c:394
 | in_atomic(): 1, irqs_disabled(): 0, non_block: 1, pid: 36, name: oom_reaper
 | INFO: lockdep is turned off.
 | CPU: 3 PID: 36 Comm: oom_reaper Not tainted 5.8.0 #1
 | Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
 | Call trace:
 |  dump_backtrace+0x0/0x284
 |  show_stack+0x1c/0x28
 |  dump_stack+0xf0/0x1a4
 |  ___might_sleep+0x2bc/0x2cc
 |  unmap_stage2_range+0x160/0x1ac
 |  kvm_unmap_hva_range+0x1a0/0x1c8
 |  kvm_mmu_notifier_invalidate_range_start+0x8c/0xf8
 |  __mmu_notifier_invalidate_range_start+0x218/0x31c
 |  mmu_notifier_invalidate_range_start_nonblock+0x78/0xb0
 |  __oom_reap_task_mm+0x128/0x268
 |  oom_reap_task+0xac/0x298
 |  oom_reaper+0x178/0x17c
 |  kthread+0x1e4/0x1fc
 |  ret_from_fork+0x10/0x30

Use the new 'flags' argument to kvm_unmap_hva_range() to ensure that we
only reschedule if MMU_NOTIFIER_RANGE_BLOCKABLE is set in the notifier
flags.

Cc: <stable@vger.kernel.org>
Fixes: 8b3405e3 ("kvm: arm/arm64: Fix locking for kvm_free_stage2_pgd")
Cc: Marc Zyngier <maz@kernel.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
Message-Id: <20200811102725.7121-3-will@kernel.org>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
[will: Backport to 4.19; use 'blockable' instead of non-existent MMU_NOTIFIER_RANGE_BLOCKABLE flag]
Signed-off-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      0f090712
    • Will Deacon's avatar
      KVM: Pass MMU notifier range flags to kvm_unmap_hva_range() · a53dc164
      Will Deacon authored 
      commit fdfe7cbd upstream.

The 'flags' field of 'struct mmu_notifier_range' is used to indicate
whether invalidate_range_{start,end}() are permitted to block. In the
case of kvm_mmu_notifier_invalidate_range_start(), this field is not
forwarded on to the architecture-specific implementation of
kvm_unmap_hva_range() and therefore the backend cannot sensibly decide
whether or not to block.

Add an extra 'flags' parameter to kvm_unmap_hva_range() so that
architectures are aware as to whether or not they are permitted to block.

Cc: <stable@vger.kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
Message-Id: <20200811102725.7121-2-will@kernel.org>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
[will: Backport to 4.19; use 'blockable' instead of non-existent range flags]
Signed-off-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      a53dc164
    • Stephen Boyd's avatar
      clk: Evict unregistered clks from parent caches · 903c6bd9
      Stephen Boyd authored 
      commit bdcf1dc2 upstream.

We leave a dangling pointer in each clk_core::parents array that has an
unregistered clk as a potential parent when that clk_core pointer is
freed by clk{_hw}_unregister(). It is impossible for the true parent of
a clk to be set with clk_set_parent() once the dangling pointer is left
in the cache because we compare parent pointers in
clk_fetch_parent_index() instead of checking for a matching clk name or
clk_hw pointer.

Before commit ede77858 ("clk: Remove global clk traversal on fetch
parent index"), we would check clk_hw pointers, which has a higher
chance of being the same between registration and unregistration, but it
can still be allocated and freed by the clk provider. In fact, this has
been a long standing problem since commit da0f0b2c ("clk: Correct
lookup logic in clk_fetch_parent_index()") where we stopped trying to
compare clk names and skipped over entries in the cache that weren't
NULL.

There are good (performance) reasons to not do the global tree lookup in
cases where the cache holds dangling pointers to parents that have been
unregistered. Let's take the performance hit on the uncommon
registration path instead. Loop through all the clk_core::parents arrays
when a clk is unregistered and set the entry to NULL when the parent
cache entry and clk being unregistered are the same pointer. This will
fix this problem and avoid the overhead for the "normal" case.

Based on a patch by Bjorn Andersson.

Fixes: da0f0b2c ("clk: Correct lookup logic in clk_fetch_parent_index()")
Reviewed-by: default avatarBjorn Andersson <bjorn.andersson@linaro.org>
Tested-by: default avatarSai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: default avatarStephen Boyd <sboyd@kernel.org>
Link: https://lkml.kernel.org/r/20190828181959.204401-1-sboyd@kernel.orgTested-by: default avatarNaresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      903c6bd9
    • Juergen Gross's avatar
      xen: don't reschedule in preemption off sections · da1754a2
      Juergen Gross authored 
      For support of long running hypercalls xen_maybe_preempt_hcall() is
calling cond_resched() in case a hypercall marked as preemptible has
been interrupted.

Normally this is no problem, as only hypercalls done via some ioctl()s
are marked to be preemptible. In rare cases when during such a
preemptible hypercall an interrupt occurs and any softirq action is
started from irq_exit(), a further hypercall issued by the softirq
handler will be regarded to be preemptible, too. This might lead to
rescheduling in spite of the softirq handler potentially having set
preempt_disable(), leading to splats like:

BUG: sleeping function called from invalid context at drivers/xen/preempt.c:37
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 20775, name: xl
INFO: lockdep is turned off.
CPU: 1 PID: 20775 Comm: xl Tainted: G D W 5.4.46-1_prgmr_debug.el7.x86_64 #1
Call Trace:
<IRQ>
dump_stack+0x8f/0xd0
___might_sleep.cold.76+0xb2/0x103
xen_maybe_preempt_hcall+0x48/0x70
xen_do_hypervisor_callback+0x37/0x40
RIP: e030:xen_hypercall_xen_version+0xa/0x20
Code: ...
RSP: e02b:ffffc900400dcc30 EFLAGS: 00000246
RAX: 000000000004000d RBX: 0000000000000200 RCX: ffffffff8100122a
RDX: ffff88812e788000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffffff83ee3ad0 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: ffff8881824aa0b0
R13: 0000000865496000 R14: 0000000865496000 R15: ffff88815d040000
? xen_hypercall_xen_version+0xa/0x20
? xen_force_evtchn_callback+0x9/0x10
? check_events+0x12/0x20
? xen_restore_fl_direct+0x1f/0x20
? _raw_spin_unlock_irqrestore+0x53/0x60
? debug_dma_sync_single_for_cpu+0x91/0xc0
? _raw_spin_unlock_irqrestore+0x53/0x60
? xen_swiotlb_sync_single_for_cpu+0x3d/0x140
? mlx4_en_process_rx_cq+0x6b6/0x1110 [mlx4_en]
? mlx4_en_poll_rx_cq+0x64/0x100 [mlx4_en]
? net_rx_action+0x151/0x4a0
? __do_softirq+0xed/0x55b
? irq_exit+0xea/0x100
? xen_evtchn_do_upcall+0x2c/0x40
? xen_do_hypervisor_callback+0x29/0x40
</IRQ>
? xen_hypercall_domctl+0xa/0x20
? xen_hypercall_domctl+0x8/0x20
? privcmd_ioctl+0x221/0x990 [xen_privcmd]
? do_vfs_ioctl+0xa5/0x6f0
? ksys_ioctl+0x60/0x90
? trace_hardirqs_off_thunk+0x1a/0x20
? __x64_sys_ioctl+0x16/0x20
? do_syscall_64+0x62/0x250
? entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fix that by testing preempt_count() before calling cond_resched().

In kernel 5.8 this can't happen any more due to the entry code rework
(more than 100 patches, so not a candidate for backporting).

The issue was introduced in kernel 4.3, so this patch should go into
all stable kernels in [4.3 ... 5.7].
Reported-by: default avatarSarah Newman <srn@prgmr.com>
Fixes: 0fa2f5cb ("sched/preempt, xen: Use need_resched() instead of should_resched()")
Cc: Sarah Newman <srn@prgmr.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Tested-by: default avatarChris Brannon <cmb@prgmr.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      da1754a2
    • Peter Xu's avatar
      mm/hugetlb: fix calculation of adjust_range_if_pmd_sharing_possible · 734654ae
      Peter Xu authored 
      commit 75802ca6 upstream.

This is found by code observation only.

Firstly, the worst case scenario should assume the whole range was covered
by pmd sharing.  The old algorithm might not work as expected for ranges
like (1g-2m, 1g+2m), where the adjusted range should be (0, 1g+2m) but the
expected range should be (0, 2g).

Since at it, remove the loop since it should not be required.  With that,
the new code should be faster too when the invalidating range is huge.

Mike said:

: With range (1g-2m, 1g+2m) within a vma (0, 2g) the existing code will only
: adjust to (0, 1g+2m) which is incorrect.
:
: We should cc stable.  The original reason for adjusting the range was to
: prevent data corruption (getting wrong page).  Since the range is not
: always adjusted correctly, the potential for corruption still exists.
:
: However, I am fairly confident that adjust_range_if_pmd_sharing_possible
: is only gong to be called in two cases:
:
: 1) for a single page
: 2) for range == entire vma
:
: In those cases, the current code should produce the correct results.
:
: To be safe, let's just cc stable.

Fixes: 017b1660 ("mm: migration: fix migration of huge PMD shared pages")
Signed-off-by: default avatarPeter Xu <peterx@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200730201636.74778-1-peterx@redhat.comSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      734654ae
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7