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| author | Juergen Gross <jgross@suse.com> | 2020-10-09 16:42:25 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-10-22 12:37:23 +0200 |
| commit | abee7c494d8c41bb388839bccc47e06247f0d7de (patch) | |
| tree | 0b904d33a73260c4ea96b1cd20322416505de3e0 /mm/memory.c | |
| parent | c3b484c439b0bab7a698495f33ef16286a1000c4 (diff) | |
x86/alternative: Don't call text_poke() in lazy TLB modex86-urgent-2020-10-27
When running in lazy TLB mode the currently active page tables might
be the ones of a previous process, e.g. when running a kernel thread.
This can be problematic in case kernel code is being modified via
text_poke() in a kernel thread, and on another processor exit_mmap()
is active for the process which was running on the first cpu before
the kernel thread.
As text_poke() is using a temporary address space and the former
address space (obtained via cpu_tlbstate.loaded_mm) is restored
afterwards, there is a race possible in case the cpu on which
exit_mmap() is running wants to make sure there are no stale
references to that address space on any cpu active (this e.g. is
required when running as a Xen PV guest, where this problem has been
observed and analyzed).
In order to avoid that, drop off TLB lazy mode before switching to the
temporary address space.
Fixes: cefa929c034eb5d ("x86/mm: Introduce temporary mm structs")
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201009144225.12019-1-jgross@suse.com
Diffstat (limited to 'mm/memory.c')
0 files changed, 0 insertions, 0 deletions