On Mon, Oct 09, 2023 at 04:08:13PM +0530, Naresh Kamboju wrote:
On Sun, 8 Oct 2023 at 21:09, Roman Gushchin roman.gushchin@linux.dev wrote:
On Sun, Oct 08, 2023 at 11:30:52AM +0530, Naresh Kamboju wrote:
While running selftests: cgroup: test_kmem on FVP following kernel crash noticed on Linux next 6.6.0-rc4-next-20231006.
Hi Naresh!
Thank you for the report!
I've tried to reproduce it, but wasn't successful so far: I've run test_kmem for several hundred times and haven't seen the crash.
If you look at the problematic test case is selftests: cgroup: test_core
Ah, got it, and immediately reproduced (and fixed). Thank you once again for all your effort!
The problem happens because some kernel allocations happen after mem_cgroup_exit(), which was dropping the reference to task->objcg, but not zeroing the pointer, so it eventually caused a double-free.
I gonna post an updated version of my patchset, which introduced the issue, with the fix merged (and some other minor changes).
Thanks!
I recommend to run ./run_kselftest.sh -c cgroup
Can you, please, provide some additional information? How easy to reproduce it?
It is always reproducible on qemu-arm64, FVP, x86 with a given config.
Do you see it every time or with some probability?
Always with selftests: cgroup: test_core. I generally run all selftests: cgroup: *
Do you see it on other platforms?
qemu-arm64, FVP, x86.
Can you, please, check where exactly the crash happens using addr2line?
I have provided links to build, test logs and steps to reproduce scripts.
Is this an interesting log ?
# selftests: cgroup: test_core # ok 1 test_cgcore_internal_process_constraint # ok 2 test_cgcore_top_down_constraint_enable # ok 3 test_cgcore_top_down_constraint_disable # ok 4 test_cgcore_no_internal_process_constraint_on_threads # ok 5 test_cgcore_parent_becomes_threaded # ok 6 test_cgcore_invalid_domain # ok 7 test_cgcore_populated # ok 8 test_cgcore_proc_migration # ok 9 test_cgcore_thread_migration # ok 10 test_cgcore_destroy # ok 11 test_cgcore_lesser_euid_open # ok 12 test_cgcore_lesser_ns_open <1>[ 188.504854] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 <1>[ 188.505724] Mem abort info: <1>[ 188.506036] ESR = 0x0000000096000044 <1>[ 188.507539] EC = 0x25: DABT (current EL), IL = 32 bits <1>[ 188.508268] SET = 0, FnV = 0 <1>[ 188.508895] EA = 0, S1PTW = 0 <1>[ 188.509517] FSC = 0x04: level 0 translation fault <1>[ 188.510279] Data abort info: <1>[ 188.511513] ISV = 0, ISS = 0x00000044, ISS2 = 0x00000000 <1>[ 188.512757] CM = 0, WnR = 1, TnD = 0, TagAccess = 0 <1>[ 188.513333] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 <1>[ 188.514316] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000104934000 <1>[ 188.516277] [0000000000000000] pgd=0000000000000000, p4d=0000000000000000 <0>[ 188.517886] Internal error: Oops: 0000000096000044 [#1] PREEMPT SMP <4>[ 188.518838] Modules linked in: crct10dif_ce sm3_ce sm3 sha3_ce sha512_ce sha512_arm64 fuse drm backlight dm_mod ip_tables x_tables <4>[ 188.521105] CPU: 0 PID: 57 Comm: kworker/0:2 Not tainted 6.6.0-rc4-next-20231006 #1 <4>[ 188.521750] Hardware name: linux,dummy-virt (DT) <4>[ 188.522915] Workqueue: cgroup_destroy css_free_rwork_fn <4>[ 188.523572] pstate: 03400009 (nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) <4>[ 188.524569] pc : percpu_ref_put_many.constprop.0 (arch/arm64/include/asm/atomic_lse.h:169 (discriminator 1) arch/arm64/include/asm/atomic_lse.h:184 (discriminator 1) arch/arm64/include/asm/atomic_lse.h:204 (discriminator 1) arch/arm64/include/asm/atomic.h:92 (discriminator 1) include/linux/atomic/atomic-arch-fallback.h:2886 (discriminator 1) include/linux/atomic/atomic-arch-fallback.h:4351 (discriminator 1) include/linux/atomic/atomic-long.h:1543 (discriminator 1) include/linux/atomic/atomic-instrumented.h:4486 (discriminator 1) include/linux/percpu-refcount.h:334 (discriminator 1)) <4>[ 188.525451] lr : percpu_ref_put_many.constprop.0 (include/linux/percpu-refcount.h:174 (discriminator 2) include/linux/percpu-refcount.h:332 (discriminator 2)) <4>[ 188.526230] sp : ffff8000803d3ca0 <4>[ 188.526902] x29: ffff8000803d3ca0 x28: 0000000000000000 x27: 0000000000000000 <4>[ 188.527976] x26: 0000000000000000 x25: ffff0000c1112e80 x24: ffff0000c002da05 <4>[ 188.528965] x23: 0000000000000030 x22: ffffafd0c976a000 x21: ffffafd0c976cb70 <4>[ 188.529927] x20: ffff0000d67fa000 x19: ffff0000d32f44c0 x18: 0000000000000000 <4>[ 188.531096] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 <4>[ 188.532244] x14: 0000000000000004 x13: ffffafd0c9787258 x12: 0000000000000000 <4>[ 188.533548] x11: ffff0000c0402e58 x10: ffff0000c0402db0 x9 : ffffafd0c6f86a90 <4>[ 188.535274] x8 : ffff8000803d3b68 x7 : 0000000000000000 x6 : 0000000000000001 <4>[ 188.536318] x5 : ffffafd0c976a000 x4 : ffffafd0c976a288 x3 : 0000000000000000 <4>[ 188.537144] x2 : ffff0000c0acbe00 x1 : 0000000000000000 x0 : ffffffffffffffff <4>[ 188.538091] Call trace: <4>[ 188.538883] percpu_ref_put_many.constprop.0 (arch/arm64/include/asm/atomic_lse.h:169 (discriminator 1) arch/arm64/include/asm/atomic_lse.h:184 (discriminator 1) arch/arm64/include/asm/atomic_lse.h:204 (discriminator 1) arch/arm64/include/asm/atomic.h:92 (discriminator 1) include/linux/atomic/atomic-arch-fallback.h:2886 (discriminator 1) include/linux/atomic/atomic-arch-fallback.h:4351 (discriminator 1) include/linux/atomic/atomic-long.h:1543 (discriminator 1) include/linux/atomic/atomic-instrumented.h:4486 (discriminator 1) include/linux/percpu-refcount.h:334 (discriminator 1)) <4>[ 188.539208] __mem_cgroup_free (include/linux/find.h:203 include/linux/nodemask.h:266 mm/memcontrol.c:5446) <4>[ 188.539559] mem_cgroup_css_free (mm/memcontrol.c:5682) <4>[ 188.543093] css_free_rwork_fn (include/linux/spinlock.h:356 kernel/cgroup/cgroup.c:350 kernel/cgroup/cgroup.c:5377) <4>[ 188.544324] process_one_work (kernel/workqueue.c:2635) <4>[ 188.545045] worker_thread (kernel/workqueue.c:2697 (discriminator 2) kernel/workqueue.c:2784 (discriminator 2)) <4>[ 188.545710] kthread (kernel/kthread.c:388) <4>[ 188.546690] ret_from_fork (arch/arm64/kernel/entry.S:858) <0>[ 188.547769] Code: d65f03c0 f9400661 d503201f 92800000 (f8e00020) All code ======== 0: d65f03c0 ret 4: f9400661 ldr x1, [x19, #8] 8: d503201f nop c: 92800000 mov x0, #0xffffffffffffffff // #-1 10:* f8e00020 ldaddal x0, x0, [x1] <-- trapping instruction
Code starting with the faulting instruction
0: f8e00020 ldaddal x0, x0, [x1] <4>[ 188.549059] ---[ end trace 0000000000000000 ]--- ok 3 selftests: cgroup: test_core
Reported-by: Linux Kernel Functional Testing lkft@linaro.org Reported-by: Naresh Kamboju naresh.kamboju@linaro.org
Links: logs: https://tuxapi.tuxsuite.com/v1/groups/linaro/projects/naresh/tests/2WWLlrB6h...
Build: https://storage.tuxsuite.com/public/linaro/naresh/builds/2WWGnN6pGnGdueSyID8... Config: https://storage.tuxsuite.com/public/linaro/naresh/builds/2WWGnN6pGnGdueSyID8...
Steps to reproduce: