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. Guenter
Fixes: 4e1c44b3db79 ("kunit, slub: add test_kfree_rcu() and test_leak_destroy()") Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx> Closes: https://lore.kernel.org/all/6fcb1252-7990-4f0d-8027-5e83f0fb9409@xxxxxxxxxxxx/ Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx> Cc: Boqun Feng <boqun.feng@xxxxxxxxx> Cc: Uladzislau Rezki <urezki@xxxxxxxxx> Cc: rcu@xxxxxxxxxxxxxxx Cc: Brendan Higgins <brendanhiggins@xxxxxxxxxx> Cc: David Gow <davidgow@xxxxxxxxxx> Cc: Rae Moar <rmoar@xxxxxxxxxx> Cc: linux-kselftest@xxxxxxxxxxxxxxx Cc: kunit-dev@xxxxxxxxxxxxxxxx Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> --- 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 ]---
