On Thu, Oct 29, 2020 at 12:47:24PM -0700, Paul E. McKenney wrote: > On Thu, Oct 29, 2020 at 05:50:19PM +0100, Uladzislau Rezki (Sony) wrote: > > A CONFIG_PREEMPT_COUNT is unconditionally enabled, thus a page > > can be obtained directly from a kvfree_rcu() path. To distinguish > > that and take a decision the preemptable() macro is used when it > > is save to enter allocator. > > > > It means that refilling a cache is not important from timing point > > of view. Switch to a delayed work, so the actual work is queued from > > the timer interrupt with 1 jiffy delay. An immediate placing a task > > on a current CPU can lead to rq->lock double lock. That is why a > > delayed method is in place. > > > > Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx> > > Thank you, Uladzislau! > > I applied this on top of v5.10-rc1 and got the following from the > single-CPU builds: > > SYNC include/config/auto.conf.cmd > DESCEND objtool > CC kernel/bounds.s > CALL scripts/atomic/check-atomics.sh > UPD include/generated/bounds.h > CC arch/x86/kernel/asm-offsets.s > In file included from ./include/asm-generic/atomic-instrumented.h:20:0, > from ./include/linux/atomic.h:82, > from ./include/linux/crypto.h:15, > from arch/x86/kernel/asm-offsets.c:9: > ./include/linux/pagemap.h: In function ‘__page_cache_add_speculative’: > ./include/linux/build_bug.h:30:34: error: called object is not a function or function pointer > #define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e)))) > ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > ./include/linux/mmdebug.h:45:25: note: in expansion of macro ‘BUILD_BUG_ON_INVALID’ > #define VM_BUG_ON(cond) BUILD_BUG_ON_INVALID(cond) > ^~~~~~~~~~~~~~~~~~~~ > ./include/linux/pagemap.h:207:2: note: in expansion of macro ‘VM_BUG_ON’ > VM_BUG_ON(preemptible()) > ^~~~~~~~~ > scripts/Makefile.build:117: recipe for target 'arch/x86/kernel/asm-offsets.s' failed > make[1]: *** [arch/x86/kernel/asm-offsets.s] Error 1 > Makefile:1199: recipe for target 'prepare0' failed > make: *** [prepare0] Error 2 > > I vaguely recall something like this showing up in the previous series > and that we did something or another to address it. Could you please > check against the old series at -rcu branch dev.2020.10.22a? (I verified > that the old series does run correctly in the single-CPU scenarios.) > I see the same build error. Will double check if we have similar in the previous series also. It looks like the error is caused by the Thomas series. Will check! -- Vlad Rezki
