On Wed, Nov 28, 2018 at 5:21 AM Qian Cai <cai@xxxxxx> wrote: > On 11/10/18 11:59 AM, Catalin Marinas wrote: > > On Sat, Nov 10, 2018 at 10:08:10AM -0500, Qian Cai wrote: > >> On Nov 8, 2018, at 4:23 PM, Qian Cai <cai@xxxxxx> wrote: > >>> The maximum value for DEBUG_KMEMLEAK_EARLY_LOG_SIZE is only 40000, so it > >>> disables kmemleak every time on this aarch64 server running the latest mainline > >>> (b00d209). > >>> > >>> # echo scan > /sys/kernel/debug/kmemleak > >>> -bash: echo: write error: Device or resource busy > >>> > >>> Any idea on how to enable kmemleak there? > >> > >> I have managed to hard-code DEBUG_KMEMLEAK_EARLY_LOG_SIZE to 600000, > > > > That's quite a high number, I wouldn't have thought it is needed. > > Basically the early log buffer is only used until the slub allocator > > gets initialised and kmemleak_init() is called from start_kernel(). I > > don't know what allocates that much memory so early. > > > > It turned out that kmemleak does not play well with KASAN on those aarch64 (HPE > Apollo 70 and Huawei TaiShan 2280) servers. > > After calling start_kernel()->setup_arch()->kasan_init(), kmemleak early log > buffer went from something like from 280 to 260000. The multitude of > kmemleak_alloc() calls is, > > for_each_memblock(memory, reg) x \ > while (pgdp++, addr = next, addr != end) x \ > while (ptep++, addr = next, addr != end && \ pte_none(READ_ONCE(*ptep))) > > Is this expected? FTR, this should be resolved by (if put pieces together correctly): https://lkml.org/lkml/2018/11/29/191
