[merged mm-stable] mm-vmalloc-prevent-flushing-dirty-space-over-and-over.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The quilt patch titled
     Subject: mm/vmalloc: prevent flushing dirty space over and over
has been removed from the -mm tree.  Its filename was
     mm-vmalloc-prevent-flushing-dirty-space-over-and-over.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: Thomas Gleixner <tglx@linutronix.de>
Subject: mm/vmalloc: prevent flushing dirty space over and over
Date: Thu, 25 May 2023 14:57:05 +0200 (CEST)

vmap blocks which have active mappings cannot be purged.  Allocations
which have been freed are accounted for in vmap_block::dirty_min/max, so
that they can be detected in _vm_unmap_aliases() as potentially stale
TLBs.

If there are several invocations of _vm_unmap_aliases() then each of them
will flush the dirty range.  That's pointless and just increases the
probability of full TLB flushes.

Avoid that by resetting the flush range after accounting for it.  That's
safe versus other invocations of _vm_unmap_aliases() because this is all
serialized with vmap_purge_lock.

Link: https://lkml.kernel.org/r/20230525124504.692056496@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/vmalloc.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/mm/vmalloc.c~mm-vmalloc-prevent-flushing-dirty-space-over-and-over
+++ a/mm/vmalloc.c
@@ -2226,7 +2226,7 @@ static void vb_free(unsigned long addr,
 
 	spin_lock(&vb->lock);
 
-	/* Expand dirty range */
+	/* Expand the not yet TLB flushed dirty range */
 	vb->dirty_min = min(vb->dirty_min, offset);
 	vb->dirty_max = max(vb->dirty_max, offset + (1UL << order));
 
@@ -2264,7 +2264,7 @@ static void _vm_unmap_aliases(unsigned l
 			 * space to be flushed.
 			 */
 			if (!purge_fragmented_block(vb, vbq, &purge_list) &&
-			    vb->dirty && vb->dirty != VMAP_BBMAP_BITS) {
+			    vb->dirty_max && vb->dirty != VMAP_BBMAP_BITS) {
 				unsigned long va_start = vb->va->va_start;
 				unsigned long s, e;
 
@@ -2274,6 +2274,10 @@ static void _vm_unmap_aliases(unsigned l
 				start = min(s, start);
 				end   = max(e, end);
 
+				/* Prevent that this is flushed again */
+				vb->dirty_min = VMAP_BBMAP_BITS;
+				vb->dirty_max = 0;
+
 				flush = 1;
 			}
 			spin_unlock(&vb->lock);
_

Patches currently in -mm which might be from tglx@linutronix.de are