lkml.org 
[lkml]   [2018]   [Jul]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 09/10] mm,x86: shoot down lazy TLB references at exit_mmap time
Date
Shooting down lazy TLB references to an mm at exit_mmap time ensures
that no users of the mm_struct will be left anywhere in the system,
allowing it to be torn down and freed immediately.

Signed-off-by: Rik van Riel <riel@surriel.com>
Suggested-by: Andy Lutomirski <luto@kernel.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
---
arch/x86/Kconfig | 1 +
arch/x86/include/asm/mmu_context.h | 1 +
arch/x86/include/asm/tlbflush.h | 2 ++
arch/x86/mm/tlb.c | 15 +++++++++++++++
4 files changed, 19 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6d4774f203d0..ecdfc6933203 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -75,6 +75,7 @@ config X86
select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
select ARCH_MIGHT_HAVE_PC_PARPORT
select ARCH_MIGHT_HAVE_PC_SERIO
+ select ARCH_NO_ACTIVE_MM_REFCOUNTING
select ARCH_SUPPORTS_ATOMIC_RMW
select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
select ARCH_USE_BUILTIN_BSWAP
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index eeeb9289c764..529bf7bc5f75 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -238,6 +238,7 @@ static inline void arch_exit_mmap(struct mm_struct *mm)
{
paravirt_arch_exit_mmap(mm);
ldt_arch_exit_mmap(mm);
+ lazy_tlb_exit_mmap(mm);
}

#ifdef CONFIG_X86_64
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 511bf5fae8b8..3966a45367cd 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -538,6 +538,8 @@ extern void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch);
native_flush_tlb_others(mask, info)
#endif

+extern void lazy_tlb_exit_mmap(struct mm_struct *mm);
+
extern void tlb_flush_remove_tables(struct mm_struct *mm);
extern void tlb_flush_remove_tables_local(void *arg);

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index ea4ef5ceaba2..7b1add904396 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -713,6 +713,21 @@ void tlb_flush_remove_tables(struct mm_struct *mm)
put_cpu();
}

+/*
+ * At exit or execve time, all other threads of a process have disappeared,
+ * but other CPUs could still be referencing this mm in lazy TLB mode.
+ * Get rid of those references before releasing the mm.
+ */
+void lazy_tlb_exit_mmap(struct mm_struct *mm)
+{
+ int cpu = get_cpu();
+
+ if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids)
+ on_each_cpu_mask(mm_cpumask(mm), leave_mm, NULL, 1);
+
+ put_cpu();
+}
+
static void do_flush_tlb_all(void *info)
{
count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
--
2.14.4
\
 
 \ /
  Last update: 2018-07-28 23:55    [W:2.011 / U:0.584 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site