On Tue, 1 Oct 2024 at 07:55, Guenter Roeck <li...@roeck-us.net> wrote: > > On 9/30/24 11:50, Guenter Roeck wrote: > > On 9/30/24 01:37, Vlastimil Babka wrote: > >> Guenter Roeck reports that the new slub kunit tests added by commit > >> 4e1c44b3db79 ("kunit, slub: add test_kfree_rcu() and > >> test_leak_destroy()") cause a lockup on boot on several architectures > >> when the kunit tests are configured to be built-in and not modules. > >> > >> These tests invoke kfree_rcu() and kvfree_rcu_barrier() and boot > >> sequence inspection showed the runner for built-in kunit tests > >> kunit_run_all_tests() is called before setting system_state to > >> SYSTEM_RUNNING and calling rcu_end_inkernel_boot(), so this seems like a > >> likely cause. So while I was unable to reproduce the problem myself, > >> moving the call to kunit_run_all_tests() a bit later in the boot seems > >> to have fixed the lockup problem according to Guenter's limited testing. > >> > >> No kunit tests should be broken by calling the built-in executor a bit > >> later, as when compiled as modules, they are still executed even later > >> than this. > >> > > Actually, that is wrong. > > Turns out kunit_iov_iter (and other kunit tests) are marked __init. > That means those unit tests have to run before the init code is released, > and it actually _is_ harmful to run the tests after rcu_end_inkernel_boot() > because at that time free_initmem() has already been called.
Yeah: some tests are marked __init. KUnit does actually mark these with an attribute, so we can potentially split the execution up into an 'init' part which runs early, and a later part, but there are some complications if we still want to track the total number of tests and support filtering, etc. properly. That's something I think we'll look at for 6.13: in the meantime, skipping the problematic slub tests when built-in seems to be the right short-term fix. I'll look into having the built-in executor moved later for non-init tests once we've worked out how best to adapt the filter/KTAP output code to do so as cleanly as possible. Cheers, -- David > > Guenter > > >> Fixes: 4e1c44b3db79 ("kunit, slub: add test_kfree_rcu() and > >> test_leak_destroy()") > >> Reported-by: Guenter Roeck <li...@roeck-us.net> > >> Closes: > >> https://lore.kernel.org/all/6fcb1252-7990-4f0d-8027-5e83f0fb9...@roeck-us.net/ > >> Cc: "Paul E. McKenney" <paul...@kernel.org> > >> Cc: Boqun Feng <boqun.f...@gmail.com> > >> Cc: Uladzislau Rezki <ure...@gmail.com> > >> Cc: r...@vger.kernel.org > >> Cc: Brendan Higgins <brendanhigg...@google.com> > >> Cc: David Gow <david...@google.com> > >> Cc: Rae Moar <rm...@google.com> > >> Cc: linux-kselft...@vger.kernel.org > >> Cc: kunit-...@googlegroups.com > >> Signed-off-by: Vlastimil Babka <vba...@suse.cz> > >> --- > >> init/main.c | 4 ++-- > >> 1 file changed, 2 insertions(+), 2 deletions(-) > >> > >> diff --git a/init/main.c b/init/main.c > >> index > >> c4778edae7972f512d5eefe8400075ac35a70d1c..7890ebb00e84b8bd7bac28923fb1fe571b3e9ee2 > >> 100644 > >> --- a/init/main.c > >> +++ b/init/main.c > >> @@ -1489,6 +1489,8 @@ static int __ref kernel_init(void *unused) > >> rcu_end_inkernel_boot(); > >> + kunit_run_all_tests(); > >> + > >> do_sysctl_args(); > >> if (ramdisk_execute_command) { > >> @@ -1579,8 +1581,6 @@ static noinline void __init > >> kernel_init_freeable(void) > >> do_basic_setup(); > >> - kunit_run_all_tests(); > >> - > >> wait_for_initramfs(); > >> console_on_rootfs(); > >> > > Unfortunately it doesn't work. With this patch applied, I get many > > backtraces > > similar to the following, and ultimately the image crashes. This is with > > arm64. > > I do not see the problem if I drop this patch. > > > > Guenter > > > > --- > > [ 9.465871] KTAP version 1 > > [ 9.465964] # Subtest: iov_iter > > [ 9.466056] # module: kunit_iov_iter > > [ 9.466115] 1..12 > > [ 9.467000] Unable to handle kernel paging request at virtual address > > ffffc37db5c9f26c > > [ 9.467244] Mem abort info: > > [ 9.467332] ESR = 0x0000000086000007 > > [ 9.467454] EC = 0x21: IABT (current EL), IL = 32 bits > > [ 9.467576] SET = 0, FnV = 0 > > [ 9.467667] EA = 0, S1PTW = 0 > > [ 9.467762] FSC = 0x07: level 3 translation fault > > [ 9.467912] swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000042a59000 > > [ 9.468055] [ffffc37db5c9f26c] pgd=0000000000000000, > > p4d=1000000044b36003, pud=1000000044b37003, pmd=1000000044b3a003, > > pte=0000000000000000 > > [ 9.469430] Internal error: Oops: 0000000086000007 [#1] PREEMPT SMP > > [ 9.469687] Modules linked in: > > [ 9.470035] CPU: 0 UID: 0 PID: 550 Comm: kunit_try_catch Tainted: G > > N 6.12.0-rc1-00005-ga65e3eb58cdb #1 > > [ 9.470290] Tainted: [N]=TEST > > [ 9.470356] Hardware name: linux,dummy-virt (DT) > > [ 9.470530] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS > > BTYPE=--) > > [ 9.470656] pc : iov_kunit_copy_to_kvec+0x0/0x334 > > [ 9.471055] lr : kunit_try_run_case+0x6c/0x15c > > [ 9.471145] sp : ffff800080883de0 > > [ 9.471210] x29: ffff800080883e20 x28: 0000000000000000 x27: > > 0000000000000000 > > [ 9.471376] x26: 0000000000000000 x25: 0000000000000000 x24: > > ffff80008000bb68 > > [ 9.471501] x23: ffffc37db3f7093c x22: ffff80008000b940 x21: > > ffff545847af4c00 > > [ 9.471622] x20: ffff545847cd3940 x19: ffff80008000bb50 x18: > > 0000000000000006 > > [ 9.471742] x17: 6c61746f7420303a x16: 70696b7320303a6c x15: > > 0000000000000172 > > [ 9.471863] x14: 0000000000020000 x13: 0000000000000000 x12: > > ffffc37db6a600c8 > > [ 9.471983] x11: 0000000000000043 x10: 0000000000000043 x9 : > > 1fffffffffffffff > > [ 9.472122] x8 : 00000000ffffffff x7 : 000000001040d4fd x6 : > > ffffc37db70c3810 > > [ 9.472243] x5 : 0000000000000000 x4 : ffffffffc4653600 x3 : > > 000000003b9ac9ff > > [ 9.472363] x2 : 0000000000000001 x1 : ffffc37db5c9f26c x0 : > > ffff80008000bb50 > > [ 9.472572] Call trace: > > [ 9.472636] iov_kunit_copy_to_kvec+0x0/0x334 > > [ 9.472740] kunit_generic_run_threadfn_adapter+0x28/0x4c > > [ 9.472835] kthread+0x11c/0x120 > > [ 9.472903] ret_from_fork+0x10/0x20 > > [ 9.473146] Code: ???????? ???????? ???????? ???????? (????????) > > [ 9.473505] ---[ end trace 0000000000000000 ]--- > > >
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