From: Prakash Gupta <guptap@xxxxxxxxxxxxxx>
Subject: mm, page_owner: skip unnecessary stack_trace entries
The page_owner stacktrace always begin as follows:
[<ffffff987bfd48f4>] save_stack+0x40/0xc8
[<ffffff987bfd4da8>] __set_page_owner+0x3c/0x6c
These two entries do not provide any useful information and limits the
available stacktrace depth. The page_owner stacktrace was skipping caller
function from stack entries but this was missed with commit f2ca0b557107
("mm/page_owner: use stackdepot to store stacktrace")
Example page_owner entry after the patch:
Page allocated via order 0, mask 0x8(ffffff80085fb714)
PFN 654411 type Movable Block 639 type CMA Flags 0x0(ffffffbe5c7f12c0)
[<ffffff9b64989c14>] post_alloc_hook+0x70/0x80
...
[<ffffff9b651216e8>] msm_comm_try_state+0x5f8/0x14f4
[<ffffff9b6512486c>] msm_vidc_open+0x5e4/0x7d0
[<ffffff9b65113674>] msm_v4l2_open+0xa8/0x224
Link: http://lkml.kernel.org/r/1504078343-28754-2-git-send-email-guptap@xxxxxxxxxxxxxx
Fixes: f2ca0b557107 ("mm/page_owner: use stackdepot to store stacktrace")
Signed-off-by: Prakash Gupta <guptap@xxxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_owner.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN mm/page_owner.c~mm-page_owner-skip-unnecessary-stack_trace-entries mm/page_owner.c
--- a/mm/page_owner.c~mm-page_owner-skip-unnecessary-stack_trace-entries
+++ a/mm/page_owner.c
@@ -142,7 +142,7 @@ static noinline depot_stack_handle_t sav
.nr_entries = 0,
.entries = entries,
.max_entries = PAGE_OWNER_STACK_DEPTH,
- .skip = 0
+ .skip = 2
};
depot_stack_handle_t handle;
_
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