mm/vmalloc: check various alignments when debugging

Before we did not guarantee a free block with lowest start address for
allocations with alignment >= PAGE_SIZE.  Because an alignment overhead
was included into a search length like below:

     length = size + align - 1;

doing so we make sure that a bigger block would fit after applying an
alignment adjustment.  Now there is no such limitation, i.e.  any
alignment that user wants to apply will result to a lowest address of
returned free area.

Link: https://lkml.kernel.org/r/20211004142829.22222-2-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Ping Fang <pifang@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 0d835bd..d477039 100644 (file)
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1269,7 +1269,7 @@ find_vmap_lowest_linear_match(unsigned long size,
 }
 
 static void
-find_vmap_lowest_match_check(unsigned long size)
+find_vmap_lowest_match_check(unsigned long size, unsigned long align)
 {
        struct vmap_area *va_1, *va_2;
        unsigned long vstart;
@@ -1278,8 +1278,8 @@ find_vmap_lowest_match_check(unsigned long size)
        get_random_bytes(&rnd, sizeof(rnd));
        vstart = VMALLOC_START + rnd;
 
-       va_1 = find_vmap_lowest_match(size, 1, vstart);
-       va_2 = find_vmap_lowest_linear_match(size, 1, vstart);
+       va_1 = find_vmap_lowest_match(size, align, vstart);
+       va_2 = find_vmap_lowest_linear_match(size, align, vstart);
 
        if (va_1 != va_2)
                pr_emerg("not lowest: t: 0x%p, l: 0x%p, v: 0x%lx\n",
@@ -1458,7 +1458,7 @@ __alloc_vmap_area(unsigned long size, unsigned long align,
                return vend;
 
 #if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
-       find_vmap_lowest_match_check(size);
+       find_vmap_lowest_match_check(size, align);
 #endif
 
        return nva_start_addr;