* [merged mm-stable] mm-rmap-use-atomic_try_cmpxchg-in-set_tlb_ubc_flush_pending.patch removed from -mm tree
@ 2023-03-28 23:21 Andrew Morton
0 siblings, 0 replies; only message in thread
From: Andrew Morton @ 2023-03-28 23:21 UTC (permalink / raw)
To: mm-commits, ubizjak, akpm
The quilt patch titled
Subject: mm/rmap: use atomic_try_cmpxchg in set_tlb_ubc_flush_pending
has been removed from the -mm tree. Its filename was
mm-rmap-use-atomic_try_cmpxchg-in-set_tlb_ubc_flush_pending.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Uros Bizjak <ubizjak@gmail.com>
Subject: mm/rmap: use atomic_try_cmpxchg in set_tlb_ubc_flush_pending
Date: Mon, 27 Feb 2023 22:42:28 +0100
Use atomic_try_cmpxchg instead of atomic_cmpxchg (*ptr, old, new) == old
in set_tlb_ubc_flush_pending. 86 CMPXCHG instruction returns success in
ZF flag, so this change saves a compare after cmpxchg (and related move
instruction in front of cmpxchg).
Also, try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg
fails.
No functional change intended.
Link: https://lkml.kernel.org/r/20230227214228.3533299-1-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/rmap.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
--- a/mm/rmap.c~mm-rmap-use-atomic_try_cmpxchg-in-set_tlb_ubc_flush_pending
+++ a/mm/rmap.c
@@ -644,7 +644,7 @@ void try_to_unmap_flush_dirty(void)
static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable)
{
struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
- int batch, nbatch;
+ int batch;
arch_tlbbatch_add_mm(&tlb_ubc->arch, mm);
tlb_ubc->flush_required = true;
@@ -662,11 +662,8 @@ retry:
* overflow. Reset `pending' and `flushed' to be 1 and 0 if
* `pending' becomes large.
*/
- nbatch = atomic_cmpxchg(&mm->tlb_flush_batched, batch, 1);
- if (nbatch != batch) {
- batch = nbatch;
+ if (!atomic_try_cmpxchg(&mm->tlb_flush_batched, &batch, 1))
goto retry;
- }
} else {
atomic_inc(&mm->tlb_flush_batched);
}
_
Patches currently in -mm which might be from ubizjak@gmail.com are
nfs-remove-empty-if-statement-from-nfs3_prepare_get_acl.patch
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