On 10/01/2023 15:53, Jason Gunthorpe wrote:
On Tue, Jan 10, 2023 at 10:01:53AM +0200, Yishai Hadas wrote:
On 10/01/2023 7:08, Matthew Wilcox wrote:
On Mon, Jan 09, 2023 at 04:47:01PM +0200, Yishai Hadas wrote:
if (sgt_append->prv) {
+ unsigned long paddr =
+ (page_to_pfn(sg_page(sgt_append->prv)) * PAGE_SIZE +
1. page_to_pfn() * PAGE_SIZE is spelled page_to_phys()
2. physical addresses have type phys_addr_t. Oh, wait, paddr isn't a
physical address, it's a pfn because you divide by PAGE_SIZE at the end.
But you will get truncation on 32-bit, because page_to_pfn() has type
unsigned long. Anyway, this shouldn't be called paddr. Maybe last_pfn
or something?
+ sgt_append->prv->offset + sgt_append->prv->length) /
+ PAGE_SIZE;
In this area of the patch I just reverted to what we had in 6.1 [1] where we
were good.
I can send V1 and replace the 'paddr' to be called 'last_pfn' if it's really
needed.
Please change it as Matthew describes so it is clearer
Jason
OK
Once cleaning the code and renaming to 'last_pfn', could also see that
we had to use below '- 1' instead of '- PAGE_SIZE'.
The expected diff compared to V0 can be seen below.
Will repeat some testing and send V1 once be ready.
+++ b/lib/scatterlist.c
@@ -470,18 +470,16 @@ int sg_alloc_append_table_from_pages(struct
sg_append_table *sgt_append,
return -EOPNOTSUPP;
if (sgt_append->prv) {
- unsigned long paddr =
- (page_to_pfn(sg_page(sgt_append->prv)) * PAGE_SIZE +
- sgt_append->prv->offset +
sgt_append->prv->length) /
- PAGE_SIZE;
+ unsigned long last_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;
- if (page_to_pfn(pages[0]) == paddr) {
- last_pg = pfn_to_page(paddr - PAGE_SIZE);
+ if (page_to_pfn(pages[0]) == last_pfn) {
+ last_pg = pfn_to_page(last_pfn - 1);
while (n_pages && pages_are_mergeable(pages[0],
last_pg)) {
if (sgt_append->prv->length + PAGE_SIZE
> max_segment)
break;
Yishai
