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authorYishai Hadas <yishaih@nvidia.com>2023-01-11 12:10:54 +0200
committerJason Gunthorpe <jgg@nvidia.com>2023-01-16 12:08:31 -0400
commit0f097f08c9b3c1fdb6cc9f2dd423abc17d13f1a2 (patch)
tree294019f8b70ca1542e50bf0ccff1ccc605f28726 /lib
parentb3deec25847bda34e34d5d7be02f633caf000bd8 (diff)
lib/scatterlist: Fix to calculate the last_pg properly
The last_pg is wrong, it is actually the first page of the last scatterlist element. To get the last page of the last scatterlist element we have to add prv->length. So it is checking mergability against the wrong page, Further, a SG element is not guaranteed to end on a page boundary, so we have to check the sub page location also for merge eligibility. Fix the above by checking physical contiguity based on PFNs, compute the actual last page and then call pages_are_mergable(). Fixes: 1567b49d1a40 ("lib/scatterlist: add check when merging zone device pages") Link: https://lore.kernel.org/r/20230111101054.188136-1-yishaih@nvidia.com Reported-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Yishai Hadas <yishaih@nvidia.com> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Diffstat (limited to 'lib')
-rw-r--r--lib/scatterlist.c25
1 files changed, 15 insertions, 10 deletions
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index f72aa50c6654..8d7519a8f308 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -470,22 +470,27 @@ int sg_alloc_append_table_from_pages(struct sg_append_table *sgt_append,
return -EOPNOTSUPP;
if (sgt_append->prv) {
+ unsigned long next_pfn = (page_to_phys(sg_page(sgt_append->prv)) +
+ sgt_append->prv->offset + sgt_append->prv->length) / PAGE_SIZE;
+
if (WARN_ON(offset))
return -EINVAL;
/* Merge contiguous pages into the last SG */
prv_len = sgt_append->prv->length;
- last_pg = sg_page(sgt_append->prv);
- while (n_pages && pages_are_mergeable(pages[0], last_pg)) {
- if (sgt_append->prv->length + PAGE_SIZE > max_segment)
- break;
- sgt_append->prv->length += PAGE_SIZE;
- last_pg = pages[0];
- pages++;
- n_pages--;
+ if (page_to_pfn(pages[0]) == next_pfn) {
+ last_pg = pfn_to_page(next_pfn - 1);
+ while (n_pages && pages_are_mergeable(pages[0], last_pg)) {
+ if (sgt_append->prv->length + PAGE_SIZE > max_segment)
+ break;
+ sgt_append->prv->length += PAGE_SIZE;
+ last_pg = pages[0];
+ pages++;
+ n_pages--;
+ }
+ if (!n_pages)
+ goto out;
}
- if (!n_pages)
- goto out;
}
/* compute number of contiguous chunks */