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Tue, 1 Oct 2024 08:37:06 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id VBOhD7K0+2bgLwAAD6G6ig (envelope-from ); Tue, 01 Oct 2024 08:37:06 +0000 Message-ID: <5ccae4ec-0b98-4f84-89be-9ba49f75e85e@suse.cz> Date: Tue, 1 Oct 2024 10:39:35 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH slab hotfixes 2/2] kunit: move call to kunit_run_all_tests() after rcu_end_inkernel_boot() To: Guenter Roeck , Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: "Paul E. McKenney" , Boqun Feng , Uladzislau Rezki , rcu@vger.kernel.org, David Gow , Rae Moar , linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com, Brendan Higgins References: <20240930-b4-slub-kunit-fix-v1-0-32ca9dbbbc11@suse.cz> <20240930-b4-slub-kunit-fix-v1-2-32ca9dbbbc11@suse.cz> <9dd56c26-12db-4b69-af0e-fdea33bb8208@roeck-us.net> From: Vlastimil Babka Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Spam-Score: -2.80 X-Spamd-Result: default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MIME_TRACE(0.00)[0:+]; TAGGED_RCPT(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCPT_COUNT_TWELVE(0.00)[17]; ARC_NA(0.00)[]; RCVD_TLS_ALL(0.00)[]; FREEMAIL_TO(0.00)[roeck-us.net,linux-foundation.org,linux.com,google.com,linux.dev,gmail.com,vger.kernel.org,kvack.org]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[kernel.org,gmail.com,vger.kernel.org,google.com,googlegroups.com,linux.dev]; MID_RHS_MATCH_FROM(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; TO_DN_SOME(0.00)[] X-Spam-Flag: NO X-Spam-Level: On 10/1/24 1:55 AM, Guenter Roeck 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. Oh, guess that explains why the kunit_run_all_tests() executor is called so suspiciously early. Of course when built as modules, __init has a different lifetime. Guess I will just skip the two new tests using kfree_rcu() when the slub kunit is built-in then. Thanks for testing. > Guenter > >>> Fixes: 4e1c44b3db79 ("kunit, slub: add test_kfree_rcu() and >>> test_leak_destroy()") >>> Reported-by: Guenter Roeck >>> Closes: >>> https://lore.kernel.org/all/6fcb1252-7990-4f0d-8027-5e83f0fb9409@roeck-us.net/ >>> Cc: "Paul E. McKenney" >>> Cc: Boqun Feng >>> Cc: Uladzislau Rezki >>> Cc: rcu@vger.kernel.org >>> Cc: Brendan Higgins >>> Cc: David Gow >>> Cc: Rae Moar >>> Cc: linux-kselftest@vger.kernel.org >>> Cc: kunit-dev@googlegroups.com >>> Signed-off-by: Vlastimil Babka >>> --- >>>   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 ]--- >> >