[LTP] [PATCH] swapon01: swapon01: prevent OOM happening in swap process

[Li Wang]

On Mon, Mar 18, 2024 at 11:20 AM Wei Gao <wegao@suse.com> wrote:

> On Sun, Mar 17, 2024 at 05:52:01PM +0800, Li Wang wrote:
> > Hi Wei,
> >
> > Can you try this one and post the test log here?
> >
> > And again, it'd be helpful to know the config of your SUT.
> > e.g. `free -h`  `lscpu`  `uname -r`  infoformation
> >
> >
> > --- a/testcases/kernel/syscalls/swapon/swapon01.c
> > +++ b/testcases/kernel/syscalls/swapon/swapon01.c
> > @@ -37,11 +37,20 @@ static void verify_swapon(void)
> >
> >  static void setup(void)
> >  {
> > +       tst_enable_oom_protection(0);
> >         is_swap_supported(SWAP_FILE);
> > -       make_swapfile(SWAP_FILE, 10, 0);
> > +       make_swapfile(SWAP_FILE, 1024, 0);
> >
> >         SAFE_CG_PRINTF(tst_cg, "cgroup.procs", "%d", getpid());
> >         SAFE_CG_PRINTF(tst_cg, "memory.max", "%lu", TESTMEM);
> > +
> > +       if (SAFE_CG_HAS(tst_cg, "memory.swap.max"))
> > +               SAFE_CG_PRINTF(tst_cg, "memory.swap.max", "%ld", TESTMEM
> *
> > 2);
> > +}
> > +
> > +static void cleanup(void)
> > +{
> > +       tst_disable_oom_protection(0);
> >  }
> >
> >  static struct tst_test test = {
> > @@ -51,5 +60,6 @@ static struct tst_test test = {
> >         .all_filesystems = 1,
> >         .needs_cgroup_ctrls = (const char *const []){ "memory", NULL },
> >         .test_all = verify_swapon,
> > -       .setup = setup
> > +       .setup = setup,
> > +       .cleanup = cleanup
> >  };
> >
> >



>
> localhost:~ # free -h <<<< before running case
>                total        used        free      shared  buff/cache
>  available
> Mem:           3.8Gi       478Mi       3.3Gi       9.0Mi       346Mi
>  3.4Gi
> Swap:             0B          0B          0B
>

I see, it is very likely that your system has no swap space
so that the TESTMEM(1GB) can not be swapped out, then
OOM killer has to be called out.

I can reproduce your problem by disabling all swap files on my system.

So the possible fix way is to reduce the TESTMEM size and increase
the tested swapfile.

I guess this patch can work for you, have a try?

--- a/testcases/kernel/syscalls/swapon/swapon01.c
+++ b/testcases/kernel/syscalls/swapon/swapon01.c
@@ -20,7 +20,7 @@

 #define MNTPOINT       "mntpoint"
 #define SWAP_FILE      MNTPOINT"/swapfile01"
-#define TESTMEM                (1UL<<30)
+#define TESTMEM                (1UL<<24)  /* 16MB */

 static void verify_swapon(void)
 {
@@ -38,7 +38,7 @@ static void verify_swapon(void)
 static void setup(void)
 {
        is_swap_supported(SWAP_FILE);
-       make_swapfile(SWAP_FILE, 10, 0);
+       make_swapfile(SWAP_FILE, 4096, 0);

        SAFE_CG_PRINTF(tst_cg, "cgroup.procs", "%d", getpid());
        SAFE_CG_PRINTF(tst_cg, "memory.max", "%lu", TESTMEM);


-- 
Regards,
Li Wang