linux-kernel - Re: [PATCH] powerpc/kvm/radix: ignore kmemleak false positives

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Message-ID: <20200527041953.GF293451@thinks.paulus.ozlabs.org>
Date:   Wed, 27 May 2020 14:19:53 +1000
From:   Paul Mackerras <paulus@...abs.org>
To:     Qian Cai <cai@....pw>
Cc:     mpe@...erman.id.au, benh@...nel.crashing.org,
        catalin.marinas@....com, kvm-ppc@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc/kvm/radix: ignore kmemleak false positives

On Wed, May 13, 2020 at 09:39:15AM -0400, Qian Cai wrote:
> kvmppc_pmd_alloc() and kvmppc_pte_alloc() allocate some memory but then
> pud_populate() and pmd_populate() will use __pa() to reference the newly
> allocated memory.
> 
> Since kmemleak is unable to track the physical memory resulting in false
> positives, silence those by using kmemleak_ignore().
> 
> unreferenced object 0xc000201c382a1000 (size 4096):
>  comm "qemu-kvm", pid 124828, jiffies 4295733767 (age 341.250s)
>  hex dump (first 32 bytes):
>    c0 00 20 09 f4 60 03 87 c0 00 20 10 72 a0 03 87  .. ..`.... .r...
>    c0 00 20 0e 13 a0 03 87 c0 00 20 1b dc c0 03 87  .. ....... .....
>  backtrace:
>    [<000000004cc2790f>] kvmppc_create_pte+0x838/0xd20 [kvm_hv]
>    kvmppc_pmd_alloc at arch/powerpc/kvm/book3s_64_mmu_radix.c:366
>    (inlined by) kvmppc_create_pte at arch/powerpc/kvm/book3s_64_mmu_radix.c:590
>    [<00000000d123c49a>] kvmppc_book3s_instantiate_page+0x2e0/0x8c0 [kvm_hv]
>    [<00000000bb549087>] kvmppc_book3s_radix_page_fault+0x1b4/0x2b0 [kvm_hv]
>    [<0000000086dddc0e>] kvmppc_book3s_hv_page_fault+0x214/0x12a0 [kvm_hv]
>    [<000000005ae9ccc2>] kvmppc_vcpu_run_hv+0xc5c/0x15f0 [kvm_hv]
>    [<00000000d22162ff>] kvmppc_vcpu_run+0x34/0x48 [kvm]
>    [<00000000d6953bc4>] kvm_arch_vcpu_ioctl_run+0x314/0x420 [kvm]
>    [<000000002543dd54>] kvm_vcpu_ioctl+0x33c/0x950 [kvm]
>    [<0000000048155cd6>] ksys_ioctl+0xd8/0x130
>    [<0000000041ffeaa7>] sys_ioctl+0x28/0x40
>    [<000000004afc4310>] system_call_exception+0x114/0x1e0
>    [<00000000fb70a873>] system_call_common+0xf0/0x278
> unreferenced object 0xc0002001f0c03900 (size 256):
>  comm "qemu-kvm", pid 124830, jiffies 4295735235 (age 326.570s)
>  hex dump (first 32 bytes):
>    c0 00 20 10 fa a0 03 87 c0 00 20 10 fa a1 03 87  .. ....... .....
>    c0 00 20 10 fa a2 03 87 c0 00 20 10 fa a3 03 87  .. ....... .....
>  backtrace:
>    [<0000000023f675b8>] kvmppc_create_pte+0x854/0xd20 [kvm_hv]
>    kvmppc_pte_alloc at arch/powerpc/kvm/book3s_64_mmu_radix.c:356
>    (inlined by) kvmppc_create_pte at arch/powerpc/kvm/book3s_64_mmu_radix.c:593
>    [<00000000d123c49a>] kvmppc_book3s_instantiate_page+0x2e0/0x8c0 [kvm_hv]
>    [<00000000bb549087>] kvmppc_book3s_radix_page_fault+0x1b4/0x2b0 [kvm_hv]
>    [<0000000086dddc0e>] kvmppc_book3s_hv_page_fault+0x214/0x12a0 [kvm_hv]
>    [<000000005ae9ccc2>] kvmppc_vcpu_run_hv+0xc5c/0x15f0 [kvm_hv]
>    [<00000000d22162ff>] kvmppc_vcpu_run+0x34/0x48 [kvm]
>    [<00000000d6953bc4>] kvm_arch_vcpu_ioctl_run+0x314/0x420 [kvm]
>    [<000000002543dd54>] kvm_vcpu_ioctl+0x33c/0x950 [kvm]
>    [<0000000048155cd6>] ksys_ioctl+0xd8/0x130
>    [<0000000041ffeaa7>] sys_ioctl+0x28/0x40
>    [<000000004afc4310>] system_call_exception+0x114/0x1e0
>    [<00000000fb70a873>] system_call_common+0xf0/0x278
> 
> Signed-off-by: Qian Cai <cai@....pw>

Thanks, applied to my kvm-ppc-next branch.

Paul.