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mm/vmalloc: add adjust_search_size parameter

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Extend the find_vmap_lowest_match() function with one more parameter.
It is "adjust_search_size" boolean variable, so it is possible to
control an accuracy of search block if a specific alignment is required.

With this patch, a search size is always adjusted, to serve a request as
fast as possible because of performance reason.

But there is one exception though, it is short ranges where requested
size corresponds to passed vstart/vend restriction together with a
specific alignment request.  In such scenario an adjustment wold not
lead to success allocation.

Link: https://lkml.kernel.org/r/20220119143540.601149-2-urezki@gmail.com
Signed-off-by: Uladzislau Rezki <uladzislau.rezki@sony.com>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Uladzislau Rezki 2022-03-22 14:42:53 -07:00 committed by Linus Torvalds
parent 690467c81b
commit 9333fe98d0
1 changed files with 28 additions and 9 deletions
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37
mm/vmalloc.c
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@ -1189,22 +1189,28 @@ is_within_this_va(struct vmap_area *va, unsigned long size,
/*
* Find the first free block(lowest start address) in the tree,
* that will accomplish the request corresponding to passing
* parameters.
* parameters. Please note, with an alignment bigger than PAGE_SIZE,
* a search length is adjusted to account for worst case alignment
* overhead.
*/
static __always_inline struct vmap_area *
find_vmap_lowest_match(unsigned long size,
unsigned long align, unsigned long vstart)
find_vmap_lowest_match(unsigned long size, unsigned long align,
unsigned long vstart, bool adjust_search_size)
{
struct vmap_area *va;
struct rb_node *node;
unsigned long length;
/* Start from the root. */
node = free_vmap_area_root.rb_node;
/* Adjust the search size for alignment overhead. */
length = adjust_search_size ? size + align - 1 : size;
while (node) {
va = rb_entry(node, struct vmap_area, rb_node);
if (get_subtree_max_size(node->rb_left) >= size &&
if (get_subtree_max_size(node->rb_left) >= length &&
vstart < va->va_start) {
node = node->rb_left;
} else {
@ -1214,9 +1220,9 @@ find_vmap_lowest_match(unsigned long size,
/*
* Does not make sense to go deeper towards the right
* sub-tree if it does not have a free block that is
* equal or bigger to the requested search size.
* equal or bigger to the requested search length.
*/
if (get_subtree_max_size(node->rb_right) >= size) {
if (get_subtree_max_size(node->rb_right) >= length) {
node = node->rb_right;
continue;
}
@ -1232,7 +1238,7 @@ find_vmap_lowest_match(unsigned long size,
if (is_within_this_va(va, size, align, vstart))
return va;
if (get_subtree_max_size(node->rb_right) >= size &&
if (get_subtree_max_size(node->rb_right) >= length &&
vstart <= va->va_start) {
/*
* Shift the vstart forward. Please note, we update it with
@ -1280,7 +1286,7 @@ find_vmap_lowest_match_check(unsigned long size, unsigned long align)
get_random_bytes(&rnd, sizeof(rnd));
vstart = VMALLOC_START + rnd;
va_1 = find_vmap_lowest_match(size, align, vstart);
va_1 = find_vmap_lowest_match(size, align, vstart, false);
va_2 = find_vmap_lowest_linear_match(size, align, vstart);
if (va_1 != va_2)
@ -1431,12 +1437,25 @@ static __always_inline unsigned long
__alloc_vmap_area(unsigned long size, unsigned long align,
unsigned long vstart, unsigned long vend)
{
bool adjust_search_size = true;
unsigned long nva_start_addr;
struct vmap_area *va;
enum fit_type type;
int ret;
va = find_vmap_lowest_match(size, align, vstart);
/*
* Do not adjust when:
* a) align <= PAGE_SIZE, because it does not make any sense.
* All blocks(their start addresses) are at least PAGE_SIZE
* aligned anyway;
* b) a short range where a requested size corresponds to exactly
* specified [vstart:vend] interval and an alignment > PAGE_SIZE.
* With adjusted search length an allocation would not succeed.
*/
if (align <= PAGE_SIZE || (align > PAGE_SIZE && (vend - vstart) == size))
adjust_search_size = false;
va = find_vmap_lowest_match(size, align, vstart, adjust_search_size);
if (unlikely(!va))
return vend;