[PATCH v4 0/2] kexec, panic: Making crash_kexec() NMI safe

Valentin Schneider
2022-06-30T22:33:17Z

Hi folks,

Here's ~v3~ v4 where we now completely get rid of kexec_mutex.

o Patch 1 makes sure all kexec_mutex acquisitions are trylocks. This prevents
having to add any while(atomic_cmpxchg()) loops which I'd really hate to see
here. If that can't be done then I think we're better off with the combined
mutex+atomic var approach.
o Patch 2 does the mutex -> atomic var switch.

Revisions
=========

v3 -> v4
++++++++

o Someone forgot to Cc LKML on v3...

v2 -> v3
++++++++

o Dropped kexec_mutex entirely and made the atomic variable the one true lock
for kexec (Eric)

v1 -> v2
++++++++

o Changed from Peterson-like synchronization to simpler atomic_cmpxchg
(Petr)
o Slightly reworded changelog
o Added Fixes: tag. Technically should be up to since kexec can happen
in an NMI, but that isn't such a clear target

Cheers,
Valentin

Valentin Schneider (2):
kexec: Turn all kexec_mutex acquisitions into trylocks
panic, kexec: Make __crash_kexec() NMI safe

include/linux/kexec.h | 2 +-
kernel/kexec.c | 11 ++++-------
kernel/kexec_core.c | 28 ++++++++++++++++------------
kernel/kexec_file.c | 4 ++--
kernel/kexec_internal.h | 15 ++++++++++++++-
kernel/ksysfs.c | 7 ++++++-
6 files changed, 43 insertions(+), 24 deletions(-)

--
2.31.1