Re: [PATCH 2/4] lib/test_vmalloc.c: Allow built-in execution

[Dev Jain]

On 13/06/25 8:07 pm, Uladzislau Rezki wrote:
> On Fri, Jun 13, 2025 at 07:53:37PM +0530, Dev Jain wrote:
> > On 13/06/25 7:49 pm, Uladzislau Rezki wrote:
> > > Hello, Dev!
> > >
> > > > On 17/04/25 9:42 pm, Uladzislau Rezki (Sony) wrote:
> > > > > This patch removes the dependency on module loading ("m")
> > > > > for the vmalloc test suite, enabling it to be built directly
> > > > > into the kernel, so both ("=m") and ("=y") are supported.
> > > > >
> > > > > Motivation:
> > > > > - Faster debugging/testing of vmalloc code;
> > > > > - It allows to configure the test via kernel-boot parameters.
> > > > >
> > > > > Configuration example:
> > > > >      test_vmalloc.nr_threads=64
> > > > >      test_vmalloc.run_test_mask=7
> > > > >      test_vmalloc.sequential_test_order=1
> > > > >
> > > > > Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
> > > > > ---
> > > > >     lib/Kconfig.debug  | 3 +--
> > > > >     lib/test_vmalloc.c | 5 +++--
> > > > >     2 files changed, 4 insertions(+), 4 deletions(-)
> > > > >
> > > > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> > > > > index f9051ab610d54..166b9d830a85a 100644
> > > > > --- a/lib/Kconfig.debug
> > > > > +++ b/lib/Kconfig.debug
> > > > > @@ -2574,8 +2574,7 @@ config TEST_BITOPS
> > > > >     config TEST_VMALLOC
> > > > >     	tristate "Test module for stress/performance analysis of vmalloc allocator"
> > > > >     	default n
> > > > > -       depends on MMU
> > > > > -	depends on m
> > > > > +	depends on MMU
> > > > >     	help
> > > > >     	  This builds the "test_vmalloc" module that should be used for
> > > > >     	  stress and performance analysis. So, any new change for vmalloc
> > > > > diff --git a/lib/test_vmalloc.c b/lib/test_vmalloc.c
> > > > > index 4ab23e5e772d0..6d65ef725d42c 100644
> > > > > --- a/lib/test_vmalloc.c
> > > > > +++ b/lib/test_vmalloc.c
> > > > > @@ -591,10 +591,11 @@ static void do_concurrent_test(void)
> > > > >     	kvfree(tdriver);
> > > > >     }
> > > > > -static int vmalloc_test_init(void)
> > > > > +static int __init vmalloc_test_init(void)
> > > > >     {
> > > > >     	do_concurrent_test();
> > > > > -	return -EAGAIN; /* Fail will directly unload the module */
> > > > > +	/* Fail will directly unload the module */
> > > > > +	return IS_BUILTIN(CONFIG_TEST_VMALLOC) ? 0:-EAGAIN;
> > > > >     }
> > > > >     module_init(vmalloc_test_init)
> > > > Hi Uladzislau,
> > > >
> > > > Post this patch I am seeing the following problem: while booting the kernel, this test is
> > > > executed and a particular testcase triggers a warning splat from the kernel, then the boot
> > > > gets stuck for 3-4 seconds, then proceeds. I am not an expert on modules so I don't know
> > > > what happened but I am guessing that when the test fails, the delay is due to module
> > > > unloading time...do you suggest a solution? I reverted your patch and then proceeded with
> > > > my work, so apologies for not having the dmesg log, if you need it I'll replicate, although
> > > > there is some subtest which has consistently been spitting out a warning on my Apple M3 Linux
> > > > VM and I have been just ignoring it for long : )
> > > This is because CONFIG_TEST_VMALLOC=y is built-in in your case.
> > Actually, I have a usecase for test_vmalloc :) I wanted to test my
> > patches through the test, but the problem is that the moment it fails,
> > it gets unloaded and then I cannot use the test at runtime. Currently it
> > is set to =m in my .config.
> Ah. It is unloaded itself when tests are done. Do not use the
> test_vmalloc.ko directly. Instead use test_vmalloc.sh script.
>
> It is located here: ./tools/testing/selftests/mm/test_vmalloc.sh
>
> Example: sudo ./test_vmalloc.sh nr_threads=HOW-MANY-CPU-YOU-have(digit) run_test_mask=7

This is what I have been doing. Before your patch, I was able to run the test multiple
times, even in case of failure. After the patch, it fails at boot time and unloads.

> --
> Uladzislau Rezki