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authorAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>2019-09-18 19:31:03 +0530
committerMichael Ellerman <mpe@ellerman.id.au>2019-09-21 08:36:53 +1000
commit7aec584eaf1cc1a527dcbe7d80f2e44e3bfcfe1d (patch)
tree7aaa2d7c7f9f5e08c1cee0230630d9711cd4cece /arch/powerpc
parenta003365cab64b0f7988ac3ccb1da895ce0bece5e (diff)
downloadlinux-7aec584eaf1cc1a527dcbe7d80f2e44e3bfcfe1d.tar.bz2
powerpc/book3s64/radix: Remove WARN_ON in destroy_context()
On failed task initialization due to memory allocation failures, we can call into destroy_context() with process_tb entry already populated. This patch forces the process_tb entry to zero in destroy_context(). With this patch, we lose the ability to track if we are destroying a context without flushing the process table entry. WARNING: CPU: 4 PID: 6368 at arch/powerpc/mm/mmu_context_book3s64.c:246 destroy_context+0x58/0x340 NIP [c0000000000875f8] destroy_context+0x58/0x340 LR [c00000000013da18] __mmdrop+0x78/0x270 Call Trace: [c000000f7db77c80] [c00000000013da18] __mmdrop+0x78/0x270 [c000000f7db77cf0] [c0000000004d6a34] __do_execve_file.isra.13+0xbd4/0x1000 [c000000f7db77e00] [c0000000004d7428] sys_execve+0x58/0x70 [c000000f7db77e30] [c00000000000b388] system_call+0x5c/0x70 Reported-by: Priya M.A <priyama2@in.ibm.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> [mpe: Reformat/tweak comment wording] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20190918140103.24395-1-aneesh.kumar@linux.ibm.com
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/mm/book3s64/mmu_context.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/arch/powerpc/mm/book3s64/mmu_context.c b/arch/powerpc/mm/book3s64/mmu_context.c
index 2d0cb5ba9a47..0ba30b8b935b 100644
--- a/arch/powerpc/mm/book3s64/mmu_context.c
+++ b/arch/powerpc/mm/book3s64/mmu_context.c
@@ -256,8 +256,21 @@ void destroy_context(struct mm_struct *mm)
#ifdef CONFIG_SPAPR_TCE_IOMMU
WARN_ON_ONCE(!list_empty(&mm->context.iommu_group_mem_list));
#endif
+ /*
+ * For tasks which were successfully initialized we end up calling
+ * arch_exit_mmap() which clears the process table entry. And
+ * arch_exit_mmap() is called before the required fullmm TLB flush
+ * which does a RIC=2 flush. Hence for an initialized task, we do clear
+ * any cached process table entries.
+ *
+ * The condition below handles the error case during task init. We have
+ * set the process table entry early and if we fail a task
+ * initialization, we need to ensure the process table entry is zeroed.
+ * We need not worry about process table entry caches because the task
+ * never ran with the PID value.
+ */
if (radix_enabled())
- WARN_ON(process_tb[mm->context.id].prtb0 != 0);
+ process_tb[mm->context.id].prtb0 = 0;
else
subpage_prot_free(mm);
destroy_contexts(&mm->context);