https://github.com/torvalds/linux
Revision a2b7861bb33b2538420bb5d8554153484d3f961f authored by Boqun Feng on 03 October 2017, 13:36:51 UTC, committed by Radim Krčmář on 04 October 2017, 16:28:53 UTC
Currently, in PREEMPT_COUNT=n kernel, kvm_async_pf_task_wait() could call schedule() to reschedule in some cases. This could result in accidentally ending the current RCU read-side critical section early, causing random memory corruption in the guest, or otherwise preempting the currently running task inside between preempt_disable and preempt_enable. The difficulty to handle this well is because we don't know whether an async PF delivered in a preemptible section or RCU read-side critical section for PREEMPT_COUNT=n, since preempt_disable()/enable() and rcu_read_lock/unlock() are both no-ops in that case. To cure this, we treat any async PF interrupting a kernel context as one that cannot be preempted, preventing kvm_async_pf_task_wait() from choosing the schedule() path in that case. To do so, a second parameter for kvm_async_pf_task_wait() is introduced, so that we know whether it's called from a context interrupting the kernel, and the parameter is set properly in all the callsites. Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wanpeng Li <wanpeng.li@hotmail.com> Cc: stable@vger.kernel.org Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
1 parent 2fb1e94
Tip revision: a2b7861bb33b2538420bb5d8554153484d3f961f authored by Boqun Feng on 03 October 2017, 13:36:51 UTC
kvm/x86: Avoid async PF preempting the kernel incorrectly
kvm/x86: Avoid async PF preempting the kernel incorrectly
Tip revision: a2b7861
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certs | ||
crypto | ||
drivers | ||
firmware | ||
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include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
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.cocciconfig | -rw-r--r-- | 59 bytes |
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.mailmap | -rw-r--r-- | 8.1 KB |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 96.1 KB |
Kbuild | -rw-r--r-- | 2.2 KB |
Kconfig | -rw-r--r-- | 252 bytes |
MAINTAINERS | -rw-r--r-- | 420.3 KB |
Makefile | -rw-r--r-- | 58.2 KB |
README | -rw-r--r-- | 722 bytes |
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