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Subject[PATCH] dma-debug: fix soft lockup when a lot of debug are enabled
Date
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.

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;
--
2.19.2
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