Messages in this thread Patch in this message | | | Subject | Re: [PATCH] dma-debug: fix soft lockup when a lot of debug are enabled | From | Robin Murphy <> | Date | Tue, 11 Dec 2018 11:51:14 +0000 |
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Hi Anders,
On 11/12/2018 10:36, Anders Roxell wrote: > When running a kernel in qemu with enough debugging options (slub-debug, > ftrace, kcov, kasan, ubsan, ...) enabled together, that results in a > slow initcall. So a 'watchdog: BUG: soft lockup' happens: > > [ 44.105619] Call trace: > [ 44.106709] __slab_alloc+0x70/0x88 > [ 44.107757] kmem_cache_alloc_trace+0x13c/0x590 > [ 44.108764] prealloc_memory+0xb8/0x240 > [ 44.109768] dma_debug_init+0x174/0x1f0 > [ 44.110725] do_one_initcall+0x430/0x8b0 > [ 44.111719] do_initcall_level+0x548/0x5b4 > [ 44.112672] do_initcalls+0x28/0x4c > [ 44.113628] do_basic_setup+0x34/0x3c > [ 44.114559] kernel_init_freeable+0x194/0x24c > [ 44.115570] kernel_init+0x24/0x18c > [ 44.116498] ret_from_fork+0x10/0x18 > > Rework to call cond_resched(), in the function prealloc_memory()'s > for-loop.
Funnily enough I've just done a bit of work in this area which should make allocation a lot more efficient - would you mind giving this series a spin on the same setup to see how much it helps the performance?
https://lore.kernel.org/lkml/cover.1544447601.git.robin.murphy@arm.com/
Thanks, Robin.
> > Signed-off-by: Anders Roxell <anders.roxell@linaro.org> > --- > kernel/dma/debug.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c > index 231ca4628062..2abdc265aec4 100644 > --- a/kernel/dma/debug.c > +++ b/kernel/dma/debug.c > @@ -767,6 +767,7 @@ static int prealloc_memory(u32 num_entries) > int i; > > for (i = 0; i < num_entries; ++i) { > + cond_resched(); > entry = kzalloc(sizeof(*entry), GFP_KERNEL); > if (!entry) > goto out_err; >
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