On 8/10/23 09:47, Xiaolei Wang wrote:
> The kmemleak_late_init() is defined as a late_initcall. The current
> implementation of set_track_prepare() depends on the kmemleak init.
> That also means there is no call trace for the memory leak which object
> is created before the kmemleak_late_init().
So if I understand correctly, we have the following sequence of events durin
boot
...
A: stack_depot is initialized
...
B: kmemleak is initialized
...
before this patchset, we can miss allocations before B, aftewards only
before A (which can't be helped), so we now have between A and B.
That's nice, but it's weird that can record kmemleak when
!kmemleak_initialized. Why can't it be initialized sooner in that case?
> In a previous patch, we have fixed a bug in stack_depot_save() so that
> it can be invoked even before stack depot is initialized. So there is
> no reason to check the kmemleak_initialized in set_track_prepare().
> So delete the kmemleak_initialized judgment in set_track_prepare()
>
> unreferenced object 0xc674ca80 (size 64):
> comm "swapper/0", pid 1, jiffies 4294938337 (age 204.880s)
> hex dump (first 32 bytes):
> 80 55 75 c6 80 54 75 c6 00 55 75 c6 80 52 75 c6 .Uu..Tu..Uu..Ru.
> 00 53 75 c6 00 00 00 00 00 00 00 00 00 00 00 00 .Su..........
>
> Fixes: 56a61617dd22 ("mm: use stack_depot for recording kmemleak's backtrace")
> Signed-off-by: Xiaolei Wang <xiaolei.wang@xxxxxxxxxxxxx>
> ---
> mm/kmemleak.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
> index a2d34226e3c8..c9f2f816db19 100644
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -610,8 +610,6 @@ static noinline depot_stack_handle_t set_track_prepare(void)
> unsigned long entries[MAX_TRACE];
> unsigned int nr_entries;
>
> - if (!kmemleak_initialized)
> - return 0;
> nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3);
> trace_handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT);
>
