Messages in this thread Patch in this message |  | | Date | Mon, 9 Dec 2019 14:47:46 +0530 | From | Bharata B Rao <> | Subject | Re: [PATCH 00/16] The new slab memory controller |
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Hi,
I see the below crash during early boot when I try this patchset on PowerPC host. I am on new_slab.rfc.v5.3 branch.
BUG: Unable to handle kernel data access at 0x81030236d1814578 Faulting instruction address: 0xc0000000002cc314 Oops: Kernel access of bad area, sig: 11 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV Modules linked in: ip_tables x_tables autofs4 sr_mod cdrom usbhid bnx2x crct10dif_vpmsum crct10dif_common mdio libcrc32c crc32c_vpmsum CPU: 31 PID: 1752 Comm: keyboard-setup. Not tainted 5.3.0-g9bd85fd72a0c #155 NIP: c0000000002cc314 LR: c0000000002cc2e8 CTR: 0000000000000000 REGS: c000001e40f378b0 TRAP: 0380 Not tainted (5.3.0-g9bd85fd72a0c) MSR: 900000010280b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]> CR: 44022224 XER: 00000000 CFAR: c0000000002c6ad4 IRQMASK: 1 GPR00: c0000000000b8a40 c000001e40f37b40 c000000000ed9600 0000000000000000 GPR04: 0000000000000023 0000000000000010 c000001e40f37b24 c000001e3cba3400 GPR08: 0000000000000020 81030218815f4578 0000001e50220000 0000000000000030 GPR12: 0000000000002200 c000001fff774d80 0000000000000000 00000001072600d8 GPR16: 0000000000000000 c0000000000bbaac 0000000000000000 0000000000000000 GPR20: c000001e40f37c48 0000000000000001 0000000000000000 c000001e3cba3400 GPR24: c000001e40f37dd8 0000000000000000 c000000000fa0d58 0000000000000000 GPR28: c000001e3a080080 c000001e32da0100 0000000000000118 0000000000000010 NIP [c0000000002cc314] __mod_memcg_state+0x58/0xd0 LR [c0000000002cc2e8] __mod_memcg_state+0x2c/0xd0 Call Trace: [c000001e40f37b90] [c0000000000b8a40] account_kernel_stack+0xa4/0xe4 [c000001e40f37bd0] [c0000000000ba4a4] copy_process+0x2b4/0x16f0 [c000001e40f37cf0] [c0000000000bbaac] _do_fork+0x9c/0x3e4 [c000001e40f37db0] [c0000000000bc030] sys_clone+0x74/0xa8 [c000001e40f37e20] [c00000000000bb34] ppc_clone+0x8/0xc Instruction dump: 4bffa7e9 2fa30000 409e007c 395efffb 3d000020 2b8a0001 409d0008 39000020 e93d0718 e94d0028 7bde1f24 7d29f214 <7ca9502a> 7fff2a14 7fe9fe76 7d27fa78
Looks like page->mem_cgroup_vec is allocated but not yet initialized with memcg pointers when we try to access them.
I did get past the crash by initializing the pointers like this in account_kernel_stack(), but I am pretty sure that this is not the place to do this:
diff --git a/kernel/fork.c b/kernel/fork.c index 541fd805fb88..be21419feae2 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -380,13 +380,26 @@ static void account_kernel_stack(struct task_struct *tsk, int account) * All stack pages are in the same zone and belong to the * same memcg. */ - struct page *first_page = virt_to_page(stack); + struct page *first_page = virt_to_head_page((stack)); + unsigned long off; + struct mem_cgroup_ptr *memcg_ptr; + struct mem_cgroup *memcg; mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB, THREAD_SIZE / 1024 * account); - mod_memcg_page_state(first_page, MEMCG_KERNEL_STACK_KB, + if (!first_page->mem_cgroup_vec) + return; + off = obj_to_index(task_struct_cachep, first_page, stack); + memcg_ptr = first_page->mem_cgroup_vec[off]; + if (!memcg_ptr) + return; + rcu_read_lock(); + memcg = memcg_ptr->memcg; + if (memcg) + __mod_memcg_state(memcg, MEMCG_KERNEL_STACK_KB, account * (THREAD_SIZE / 1024)); + rcu_read_unlock(); } }
Regards, Bharata.
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