From: Nadav Amit <nadav.amit@gmail.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Nadav Amit <namit@vmware.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>, Yu Zhao <yuzhao@google.com>,
Nick Piggin <npiggin@gmail.com>,
x86@kernel.org
Subject: [RFC 08/20] mm: store completed TLB generation
Date: Sat, 30 Jan 2021 16:11:20 -0800 [thread overview]
Message-ID: <20210131001132.3368247-9-namit@vmware.com> (raw)
In-Reply-To: <20210131001132.3368247-1-namit@vmware.com>
From: Nadav Amit <namit@vmware.com>
To detect deferred TLB flushes in fine granularity, we need to keep
track on the completed TLB flush generation for each mm.
Add logic to track for each mm the tlb_gen_completed, which tracks the
completed TLB generation. It is the arch responsibility to call
mark_mm_tlb_gen_done() whenever a TLB flush is completed.
Start the generation numbers from 1 instead of 0. This would allow later
to detect whether flushes of a certain generation were completed.
Signed-off-by: Nadav Amit <namit@vmware.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: x86@kernel.org
---
arch/x86/mm/tlb.c | 10 ++++++++++
include/asm-generic/tlb.h | 33 +++++++++++++++++++++++++++++++++
include/linux/mm_types.h | 15 ++++++++++++++-
3 files changed, 57 insertions(+), 1 deletion(-)
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 7ab21430be41..d17b5575531e 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -14,6 +14,7 @@
#include <asm/nospec-branch.h>
#include <asm/cache.h>
#include <asm/apic.h>
+#include <asm/tlb.h>
#include "mm_internal.h"
@@ -915,6 +916,9 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids)
flush_tlb_others(mm_cpumask(mm), info);
+ /* Update the completed generation */
+ mark_mm_tlb_gen_done(mm, new_tlb_gen);
+
put_flush_tlb_info();
put_cpu();
}
@@ -1147,6 +1151,12 @@ void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch)
cpumask_clear(&batch->cpumask);
+ /*
+ * We cannot call mark_mm_tlb_gen_done() since we do not know which
+ * mm's should be flushed. This may lead to some unwarranted TLB
+ * flushes, but not to correction problems.
+ */
+
put_cpu();
}
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 517c89398c83..427bfcc6cdec 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -513,6 +513,39 @@ static inline void tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vm
}
#endif
+#ifdef CONFIG_ARCH_HAS_TLB_GENERATIONS
+
+/*
+ * Helper function to update a generation to have a new value, as long as new
+ * value is greater or equal to gen.
+ */
+static inline void tlb_update_generation(atomic64_t *gen, u64 new_gen)
+{
+ u64 cur_gen = atomic64_read(gen);
+
+ while (cur_gen < new_gen) {
+ u64 old_gen = atomic64_cmpxchg(gen, cur_gen, new_gen);
+
+ /* Check if we succeeded in the cmpxchg */
+ if (likely(cur_gen == old_gen))
+ break;
+
+ cur_gen = old_gen;
+ };
+}
+
+
+static inline void mark_mm_tlb_gen_done(struct mm_struct *mm, u64 gen)
+{
+ /*
+ * Update the completed generation to the new generation if the new
+ * generation is greater than the previous one.
+ */
+ tlb_update_generation(&mm->tlb_gen_completed, gen);
+}
+
+#endif /* CONFIG_ARCH_HAS_TLB_GENERATIONS */
+
/*
* tlb_flush_{pte|pmd|pud|p4d}_range() adjust the tlb->start and tlb->end,
* and set corresponding cleared_*.
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 2035ac319c2b..8a5eb4bfac59 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -571,6 +571,13 @@ struct mm_struct {
* This is not used on Xen PV.
*/
atomic64_t tlb_gen;
+
+ /*
+ * TLB generation which is guarnateed to be flushed, including
+ * all the PTE changes that were performed before tlb_gen was
+ * incremented.
+ */
+ atomic64_t tlb_gen_completed;
#endif
} __randomize_layout;
@@ -690,7 +697,13 @@ static inline bool mm_tlb_flush_nested(struct mm_struct *mm)
#ifdef CONFIG_ARCH_HAS_TLB_GENERATIONS
static inline void init_mm_tlb_gen(struct mm_struct *mm)
{
- atomic64_set(&mm->tlb_gen, 0);
+ /*
+ * Start from generation of 1, so default generation 0 will be
+ * considered as flushed and would not be regarded as an outstanding
+ * deferred invalidation.
+ */
+ atomic64_set(&mm->tlb_gen, 1);
+ atomic64_set(&mm->tlb_gen_completed, 1);
}
static inline u64 inc_mm_tlb_gen(struct mm_struct *mm)
--
2.25.1
next prev parent reply other threads:[~2021-01-31 0:16 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-31 0:11 [RFC 00/20] TLB batching consolidation and enhancements Nadav Amit
2021-01-31 0:11 ` [RFC 01/20] mm/tlb: fix fullmm semantics Nadav Amit
2021-01-31 1:02 ` Andy Lutomirski
2021-01-31 1:19 ` Nadav Amit
2021-01-31 2:57 ` Andy Lutomirski
2021-02-01 7:30 ` Nadav Amit
2021-02-01 11:36 ` Peter Zijlstra
2021-02-02 9:32 ` Nadav Amit
2021-02-02 11:00 ` Peter Zijlstra
2021-02-02 21:35 ` Nadav Amit
2021-02-03 9:44 ` Will Deacon
2021-02-04 3:20 ` Nadav Amit
2021-01-31 0:11 ` [RFC 02/20] mm/mprotect: use mmu_gather Nadav Amit
2021-01-31 0:11 ` [RFC 03/20] mm/mprotect: do not flush on permission promotion Nadav Amit
2021-01-31 1:07 ` Andy Lutomirski
2021-01-31 1:17 ` Nadav Amit
2021-01-31 2:59 ` Andy Lutomirski
[not found] ` <7a6de15a-a570-31f2-14d6-a8010296e694@citrix.com>
2021-02-01 5:58 ` Nadav Amit
2021-02-01 15:38 ` Andrew Cooper
2021-01-31 0:11 ` [RFC 04/20] mm/mapping_dirty_helpers: use mmu_gather Nadav Amit
2021-01-31 0:11 ` [RFC 05/20] mm/tlb: move BATCHED_UNMAP_TLB_FLUSH to tlb.h Nadav Amit
2021-01-31 0:11 ` [RFC 06/20] fs/task_mmu: use mmu_gather interface of clear-soft-dirty Nadav Amit
2021-01-31 0:11 ` [RFC 07/20] mm: move x86 tlb_gen to generic code Nadav Amit
2021-01-31 18:26 ` Andy Lutomirski
2021-01-31 0:11 ` Nadav Amit [this message]
2021-01-31 20:32 ` [RFC 08/20] mm: store completed TLB generation Andy Lutomirski
2021-02-01 7:28 ` Nadav Amit
2021-02-01 16:53 ` Andy Lutomirski
2021-02-01 11:52 ` Peter Zijlstra
2021-01-31 0:11 ` [RFC 09/20] mm: create pte/pmd_tlb_flush_pending() Nadav Amit
2021-01-31 0:11 ` [RFC 10/20] mm: add pte_to_page() Nadav Amit
2021-01-31 0:11 ` [RFC 11/20] mm/tlb: remove arch-specific tlb_start/end_vma() Nadav Amit
2021-02-01 12:09 ` Peter Zijlstra
2021-02-02 6:41 ` Nicholas Piggin
2021-02-02 7:20 ` Nadav Amit
2021-02-02 9:31 ` Peter Zijlstra
2021-02-02 9:54 ` Nadav Amit
2021-02-02 11:04 ` Peter Zijlstra
2021-01-31 0:11 ` [RFC 12/20] mm/tlb: save the VMA that is flushed during tlb_start_vma() Nadav Amit
2021-02-01 12:28 ` Peter Zijlstra
2021-01-31 0:11 ` [RFC 13/20] mm/tlb: introduce tlb_start_ptes() and tlb_end_ptes() Nadav Amit
2021-01-31 9:57 ` Damian Tometzki
2021-01-31 10:07 ` Damian Tometzki
2021-02-01 7:29 ` Nadav Amit
2021-02-01 13:19 ` Peter Zijlstra
2021-02-01 23:00 ` Nadav Amit
2021-01-31 0:11 ` [RFC 14/20] mm: move inc/dec_tlb_flush_pending() to mmu_gather.c Nadav Amit
2021-01-31 0:11 ` [RFC 15/20] mm: detect deferred TLB flushes in vma granularity Nadav Amit
2021-02-01 22:04 ` Nadav Amit
2021-02-02 0:14 ` Andy Lutomirski
2021-02-02 20:51 ` Nadav Amit
2021-02-04 4:35 ` Andy Lutomirski
2021-01-31 0:11 ` [RFC 16/20] mm/tlb: per-page table generation tracking Nadav Amit
2021-01-31 0:11 ` [RFC 17/20] mm/tlb: updated completed deferred TLB flush conditionally Nadav Amit
2021-01-31 0:11 ` [RFC 18/20] mm: make mm_cpumask() volatile Nadav Amit
2021-01-31 0:11 ` [RFC 19/20] lib/cpumask: introduce cpumask_atomic_or() Nadav Amit
2021-01-31 0:11 ` [RFC 20/20] mm/rmap: avoid potential races Nadav Amit
2021-08-23 8:05 ` Huang, Ying
2021-08-23 15:50 ` Nadav Amit
2021-08-24 0:36 ` Huang, Ying
2021-01-31 0:39 ` [RFC 00/20] TLB batching consolidation and enhancements Andy Lutomirski
2021-01-31 1:08 ` Nadav Amit
2021-01-31 3:30 ` Nicholas Piggin
2021-01-31 7:57 ` Nadav Amit
2021-01-31 8:14 ` Nadav Amit
2021-02-01 12:44 ` Peter Zijlstra
2021-02-02 7:14 ` Nicholas Piggin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210131001132.3368247-9-namit@vmware.com \
--to=nadav.amit@gmail.com \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=dave.hansen@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=luto@kernel.org \
--cc=namit@vmware.com \
--cc=npiggin@gmail.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=will@kernel.org \
--cc=x86@kernel.org \
--cc=yuzhao@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).