kmap_atomic() has been deprecated in favor of kmap_local_page().
Therefore, replace kmap_atomic() with kmap_local_page() in
zswap.c.
kmap_atomic() is implemented like a kmap_local_page() which also
disables page-faults and preemption (the latter only in !PREEMPT_RT
kernels). The kernel virtual addresses returned by these two API are
only valid in the context of the callers (i.e., they cannot be handed to
other threads).
With kmap_local_page() the mappings are per thread and CPU local like
in kmap_atomic(); however, they can handle page-faults and can be called
from any context (including interrupts). The tasks that call
kmap_local_page() can be preempted and, when they are scheduled to run
again, the kernel virtual addresses are restored and are still valid.
In mm/zswap.c, the blocks of code between the mappings and un-mappings
do not depend on the above-mentioned side effects of kmap_atomic(), so
that the mere replacements of the old API with the new one is all that is
required (i.e., there is no need to explicitly call pagefault_disable()
and/or preempt_disable()).
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Signed-off-by: Fabio M. De Francesco <fabio.maria.de.francesco@xxxxxxxxxxxxxxx>
---
mm/zswap.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/mm/zswap.c b/mm/zswap.c
index 74411dfdad92..699c6ee11222 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1267,16 +1267,16 @@ bool zswap_store(struct folio *folio)
}
if (zswap_same_filled_pages_enabled) {
- src = kmap_atomic(page);
+ src = kmap_local_page(page);
if (zswap_is_page_same_filled(src, &value)) {
- kunmap_atomic(src);
+ kunmap_local(src);
entry->swpentry = swp_entry(type, offset);
entry->length = 0;
entry->value = value;
atomic_inc(&zswap_same_filled_pages);
goto insert_entry;
}
- kunmap_atomic(src);
+ kunmap_local(src);
}
if (!zswap_non_same_filled_pages_enabled)
@@ -1422,9 +1422,9 @@ bool zswap_load(struct folio *folio)
spin_unlock(&tree->lock);
if (!entry->length) {
- dst = kmap_atomic(page);
+ dst = kmap_local_page(page);
zswap_fill_page(dst, entry->value);
- kunmap_atomic(dst);
+ kunmap_local(dst);
ret = true;
goto stats;
}
--
2.42.0
