On Wed, Jan 10, 2018 at 11:01:28AM +0100, Miroslav Benes wrote: > Immediate flag has been used to disable per-task consistency and patch > all tasks immediately. It could be useful if the patch doesn't change any > function or data semantics. > > However, it causes problems on its own. The consistency problem is > currently broken with respect to immediate patches. > > func a > patches 1i > 2i > 3 > > When the patch 3 is applied, only 2i function is checked (by stack > checking facility). There might be a task sleeping in 1i though. Such > task is migrated to 3, because we do not check 1i in > klp_check_stack_func() at all. > > Coming atomic replace feature would be easier to implement and more > reliable without immediate. > > Thus, remove immediate feature completely and save us from the problems. > > Note that force feature has the similar problem. However it is > considered as a last resort. If used, administrator should not apply any > new live patches and should plan for reboot into an updated kernel. > > The architectures would now need to provide HAVE_RELIABLE_STACKTRACE to > fully support livepatch. > > Signed-off-by: Miroslav Benes <mbenes@xxxxxxx> > --- > v2 changes: > - 2/2 from v1 dropped > - documentation > > Documentation/livepatch/livepatch.txt | 89 +++++++++------------------- > include/linux/livepatch.h | 4 -- > kernel/livepatch/core.c | 12 +--- > kernel/livepatch/transition.c | 49 ++------------- > samples/livepatch/livepatch-callbacks-demo.c | 15 ----- > samples/livepatch/livepatch-sample.c | 15 ----- > samples/livepatch/livepatch-shadow-fix1.c | 15 ----- > samples/livepatch/livepatch-shadow-fix2.c | 15 ----- > 8 files changed, 33 insertions(+), 181 deletions(-) Nice diffstat. Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> -- Josh -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
