From a09fad96ffb1d0da007283727235a03b813f989b Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 25 May 2023 14:57:05 +0200 Subject: mm/vmalloc: prevent flushing dirty space over and over 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 Reviewed-by: Baoquan He Reviewed-by: Christoph Hellwig Reviewed-by: Lorenzo Stoakes Cc: Uladzislau Rezki (Sony) Signed-off-by: Andrew Morton --- mm/vmalloc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'mm/vmalloc.c') diff --git a/mm/vmalloc.c b/mm/vmalloc.c index eaef5e0400db..ad9a1d9e314f 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2226,7 +2226,7 @@ static void vb_free(unsigned long addr, unsigned long size) 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 long start, unsigned long end, int flush) * 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 long start, unsigned long end, int flush) 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); -- cgit