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43fb96ae78
When waking a VM's NX huge page recovery thread, ensure the thread is
actually alive before trying to wake it. Now that the thread is spawned
on-demand during KVM_RUN, a VM without a recovery thread is reachable via
the related module params.
BUG: kernel NULL pointer dereference, address: 0000000000000040
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:vhost_task_wake+0x5/0x10
Call Trace:
<TASK>
set_nx_huge_pages+0xcc/0x1e0 [kvm]
param_attr_store+0x8a/0xd0
module_attr_store+0x1a/0x30
kernfs_fop_write_iter+0x12f/0x1e0
vfs_write+0x233/0x3e0
ksys_write+0x60/0xd0
do_syscall_64+0x5b/0x160
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x7f3b52710104
</TASK>
Modules linked in: kvm_intel kvm
CR2: 0000000000000040
Fixes: 931656b9e2 ("kvm: defer huge page recovery vhost task to later")
Cc: stable@vger.kernel.org
Cc: Keith Busch <kbusch@kernel.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20250124234623.3609069-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.