Issue observed on ARM. Whenever there is switch from user mode, we end up with invalid last entry with some user space address as below:-
save_stack+0x40/0xec __set_page_owner+0x2c/0x64 .... .... __handle_domain_irq+0x9c/0x130 gic_handle_irq+0x40/0x80 __irq_usr+0x4c/0x60 0xb6507818 So in this case last entry is not valid, which leads to allocated one more new frame for stackdepot although having all above frames exactly same. (It increases depot_index drastically) So its better to ignore that last frame in case of switch. save_stack+0x40/0xec __set_page_owner+0x2c/0x64 .... .... __handle_domain_irq+0x9c/0x130 gic_handle_irq+0x40/0x80 __irq_usr+0x4c/0x60 Signed-off-by: Vaneet Narang <v.nar...@samsung.com> Signed-off-by: Maninder Singh <maninder...@samsung.com> --- lib/stackdepot.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index f87d138..bb35b2c 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -214,6 +214,11 @@ depot_stack_handle_t depot_save_stack(struct stack_trace *trace, if (unlikely(trace->nr_entries == 0)) goto fast_exit; + if (trace->entries[trace->nr_entries - 1] < MODULES_VADDR) { + trace->entries[trace->nr_entries - 1] = ULONG_MAX; + trace->nr_entries--; + } + hash = hash_stack(trace->entries, trace->nr_entries); bucket = &stack_table[hash & STACK_HASH_MASK]; -- 1.9.1