Re: [PATCH] mm/damon/core-test: Initialise context before test in damon_test_set_attrs()

[SeongJae Park]

Also, please note that it would be very helpful if you could Cc
damon@xxxxxxxxxxxxxxx for all DAMON-related patches from the next time.  I'm
cc-ing the list.


Thanks,
SJ

On Tue, 18 Jul 2023 16:16:56 +0000 SeongJae Park <sj@xxxxxxxxxx> wrote:

> Hi Feng Tang,
> 
> On Tue, 18 Jul 2023 13:28:11 +0800 Feng Tang <feng.tang@xxxxxxxxx> wrote:
> 
> > Running kunit test for 6.5-rc1 hits one bug:
> > 
> >         ok 10 damon_test_update_monitoring_result
> >     general protection fault, probably for non-canonical address 0x1bffa5c419cfb81: 0000 [#1] PREEMPT SMP NOPTI
> >     CPU: 1 PID: 110 Comm: kunit_try_catch Tainted: G                 N 6.5.0-rc2 #15
> >     Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
> >     RIP: 0010:damon_set_attrs+0xb9/0x120
> >     Code: f8 00 00 00 4c 8d 58 e0 48 39 c3 74 ba 41 ba 59 17 b7 d1 49 8b 43 10 4d
> >     8d 4b 10 48 8d 70 e0 49 39 c1 74 50 49 8b 40 08 31 d2 <69> 4e 18 10 27 00 00
> >     49 f7 30 31 d2 48 89 c5 89 c8 f7 f5 31 d2 89
> >     RSP: 0000:ffffc900005bfd40 EFLAGS: 00010246
> >     RAX: ffffffff81159fc0 RBX: ffffc900005bfeb8 RCX: 0000000000000000
> >     RDX: 0000000000000000 RSI: 01bffa5c419cfb69 RDI: ffffc900005bfd70
> >     RBP: ffffc90000013c10 R08: ffffc900005bfdc0 R09: ffffffff81ff10ed
> >     R10: 00000000d1b71759 R11: ffffffff81ff10dd R12: ffffc90000013a78
> >     R13: ffff88810eb78180 R14: ffffffff818297c0 R15: ffffc90000013c28
> >     FS:  0000000000000000(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000
> >     CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >     CR2: 0000000000000000 CR3: 0000000002a1c001 CR4: 0000000000370ee0
> >     DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> >     DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> >     Call Trace:
> >      <TASK>
> >      damon_test_set_attrs+0x63/0x1f0
> >      kunit_generic_run_threadfn_adapter+0x17/0x30
> >      kthread+0xfd/0x130
> 
> Great.  But it would be even greater if you could this kind of output after
> decoding the addreses using 'scripts/decode_stacktrace.sh` or
> 'scripts/faddr2line' from next time if possible.
> 
> > 
> > The problem seems to be related with the damon_ctx was used without
> > being initialized. Fix it by adding the initialization.
> 
> Somehow the test always passed on my test machine, but maybe that's due to some
> different behavior of my compiler.  I agree that could be the root cause
> because 'damon_set_attrs()' calls 'damon_update_monitoring_results()', which
> accesses the context's fields including the targets list.  Since the list is
> not initialized in this test code, it would cause such error.
> 
> > 
> > Fixes: aa13779be6b7 ("mm/damon/core-test: add a test for damon_set_attrs()")
> > Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
> 
> Reviewed-by: SeongJae Park <sj@xxxxxxxxxx>
> 
> 
> Thanks,
> SJ
>