On 13.12.23 06:33, Yin Fengwei wrote:
On 2023/12/11 23:56, David Hildenbrand wrote:
Let's get rid of the compound parameter and instead define implicitly
which mappings we're adding. That is more future proof, easier to read
and harder to mess up.
Use an enum to express the granularity internally. Make the compiler
always special-case on the granularity by using __always_inline. Replace
the "compound" check by a switch-case that will be removed by the
compiler completely.
Add plenty of sanity checks with CONFIG_DEBUG_VM. Replace the
folio_test_pmd_mappable() check by a config check in the caller and
sanity checks. Convert the single user of folio_add_file_rmap_range().
This function design can later easily be extended to PUDs and to batch
PMDs. Note that for now we don't support anything bigger than
PMD-sized folios (as we cleanly separated hugetlb handling). Sanity checks
will catch if that ever changes.
Next up is removing page_remove_rmap() along with its "compound"
parameter and smilarly converting all other rmap functions.
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>
Thanks!
With one small comment.
---
include/linux/rmap.h | 47 +++++++++++++++++++++++++--
mm/memory.c | 2 +-
mm/rmap.c | 75 +++++++++++++++++++++++++++++---------------
3 files changed, 95 insertions(+), 29 deletions(-)
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index e3857d26b944..1753900f4aed 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -191,6 +191,45 @@ typedef int __bitwise rmap_t;
*/
#define RMAP_COMPOUND ((__force rmap_t)BIT(1))
+/*
+ * Internally, we're using an enum to specify the granularity. Usually,
+ * we make the compiler create specialized variants for the different
+ * granularity.
+ */
+enum rmap_mode {
+ RMAP_MODE_PTE = 0,
+ RMAP_MODE_PMD,
+};
Maybe rmap_level for enum name? To me, PTE and PMD are level instead of
mode.
Originally, I wanted to call this "enum rmap_granularity", but that
turned out rather long. Agreed that "level" is better than "mode",
something resembling "granularity" would be even better.
--
Cheers,
David / dhildenb
