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UPSTREAM: mm/cma: expose all pages to the buddy if activation of an area fails

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Right now, if activation fails, we might already have exposed some pages
to the buddy for CMA use (although they will never get actually used by
CMA), and some pages won't be exposed to the buddy at all.

Let's check for "single zone" early and on error, don't expose any pages
for CMA use - instead, expose them to the buddy available for any use.
Simply call free_reserved_page() on every single page - easier than going
via free_reserved_area(), converting back and forth between pfns and virt
addresses.

In addition, make sure to fixup totalcma_pages properly.

Example: 6 GiB QEMU VM with "... hugetlb_cma=2G movablecore=20% ...":
  [    0.006891] hugetlb_cma: reserve 2048 MiB, up to 2048 MiB per node
  [    0.006893] cma: Reserved 2048 MiB at 0x0000000100000000
  [    0.006893] hugetlb_cma: reserved 2048 MiB on node 0
  ...
  [    0.175433] cma: CMA area hugetlb0 could not be activated

Before this patch:
  # cat /proc/meminfo
  MemTotal:        5867348 kB
  MemFree:         5692808 kB
  MemAvailable:    5542516 kB
  ...
  CmaTotal:        2097152 kB
  CmaFree:         1884160 kB

After this patch:
  # cat /proc/meminfo
  MemTotal:        6077308 kB
  MemFree:         5904208 kB
  MemAvailable:    5747968 kB
  ...
  CmaTotal:              0 kB
  CmaFree:               0 kB

Note: cma_init_reserved_mem() makes sure that we always cover full
pageblocks / MAX_ORDER - 1 pages.

Link: https://lkml.kernel.org/r/20210127101813.6370-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 072355c1cf2d4f37993bcfc5894e17d0b11bb290)
Signed-off-by: Minchan Kim <minchan@google.com>
Bug: 181887812
Change-Id: Ia8b6e3b0dfef59fe36693db0d235fb75cce9e61e
This commit is contained in:
David Hildenbrand
2021-02-25 17:16:37 -08:00
committed by Suren Baghdasaryan
parent 0e0bfc41fd
commit 06080c43d2
1 changed files with 20 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

41
mm/cma.c
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@@ -98,34 +98,29 @@ static void cma_clear_bitmap(struct cma *cma, unsigned long pfn,
static void __init cma_activate_area(struct cma *cma)
{
unsigned long base_pfn = cma->base_pfn, pfn = base_pfn;
unsigned i = cma->count >> pageblock_order;
unsigned long base_pfn = cma->base_pfn, pfn;
struct zone *zone;
cma->bitmap = bitmap_zalloc(cma_bitmap_maxno(cma), GFP_KERNEL);
if (!cma->bitmap)
goto out_error;
WARN_ON_ONCE(!pfn_valid(pfn));
zone = page_zone(pfn_to_page(pfn));
/*
* alloc_contig_range() requires the pfn range specified to be in the
* same zone. Simplify by forcing the entire CMA resv range to be in the
* same zone.
*/
WARN_ON_ONCE(!pfn_valid(base_pfn));
zone = page_zone(pfn_to_page(base_pfn));
for (pfn = base_pfn + 1; pfn < base_pfn + cma->count; pfn++) {
WARN_ON_ONCE(!pfn_valid(pfn));
if (page_zone(pfn_to_page(pfn)) != zone)
goto not_in_zone;
}
do {
unsigned j;
base_pfn = pfn;
for (j = pageblock_nr_pages; j; --j, pfn++) {
WARN_ON_ONCE(!pfn_valid(pfn));
/*
* alloc_contig_range requires the pfn range
* specified to be in the same zone. Make this
* simple by forcing the entire CMA resv range
* to be in the same zone.
*/
if (page_zone(pfn_to_page(pfn)) != zone)
goto not_in_zone;
}
init_cma_reserved_pageblock(pfn_to_page(base_pfn));
} while (--i);
for (pfn = base_pfn; pfn < base_pfn + cma->count;
pfn += pageblock_nr_pages)
init_cma_reserved_pageblock(pfn_to_page(pfn));
mutex_init(&cma->lock);
@@ -139,6 +134,10 @@ static void __init cma_activate_area(struct cma *cma)
not_in_zone:
bitmap_free(cma->bitmap);
out_error:
/* Expose all pages to the buddy, they are useless for CMA. */
for (pfn = base_pfn; pfn < base_pfn + cma->count; pfn++)
free_reserved_page(pfn_to_page(pfn));
totalcma_pages -= cma->count;
cma->count = 0;
pr_err("CMA area %s could not be activated\n", cma->name);
return;