kmap_atomic() has been deprecated in favor of kmap_local_page().
Therefore, replace kmap_atomic() with kmap_local_page() in
swapfile.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/swapfile.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/swapfile.c | 34 +++++++++++++++++-----------------
1 file changed, 17 insertions(+), 17 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 4bc70f459164..8be70912e298 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1495,9 +1495,9 @@ int swp_swapcount(swp_entry_t entry)
do {
page = list_next_entry(page, lru);
- map = kmap_atomic(page);
+ map = kmap_local_page(page);
tmp_count = map[offset];
- kunmap_atomic(map);
+ kunmap_local(map);
count += (tmp_count & ~COUNT_CONTINUED) * n;
n *= (SWAP_CONT_MAX + 1);
@@ -3477,9 +3477,9 @@ int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask)
if (!(count & COUNT_CONTINUED))
goto out_unlock_cont;
- map = kmap_atomic(list_page) + offset;
+ map = kmap_local_page(list_page) + offset;
count = *map;
- kunmap_atomic(map);
+ kunmap_local(map);
/*
* If this continuation count now has some space in it,
@@ -3529,7 +3529,7 @@ static bool swap_count_continued(struct swap_info_struct *si,
spin_lock(&si->cont_lock);
offset &= ~PAGE_MASK;
page = list_next_entry(head, lru);
- map = kmap_atomic(page) + offset;
+ map = kmap_local_page(page) + offset;
if (count == SWAP_MAP_MAX) /* initial increment from swap_map */
goto init_map; /* jump over SWAP_CONT_MAX checks */
@@ -3539,27 +3539,27 @@ static bool swap_count_continued(struct swap_info_struct *si,
* Think of how you add 1 to 999
*/
while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) {
- kunmap_atomic(map);
+ kunmap_local(map);
page = list_next_entry(page, lru);
BUG_ON(page == head);
- map = kmap_atomic(page) + offset;
+ map = kmap_local_page(page) + offset;
}
if (*map == SWAP_CONT_MAX) {
- kunmap_atomic(map);
+ kunmap_local(map);
page = list_next_entry(page, lru);
if (page == head) {
ret = false; /* add count continuation */
goto out;
}
- map = kmap_atomic(page) + offset;
+ map = kmap_local_page(page) + offset;
init_map: *map = 0; /* we didn't zero the page */
}
*map += 1;
- kunmap_atomic(map);
+ kunmap_local(map);
while ((page = list_prev_entry(page, lru)) != head) {
- map = kmap_atomic(page) + offset;
+ map = kmap_local_page(page) + offset;
*map = COUNT_CONTINUED;
- kunmap_atomic(map);
+ kunmap_local(map);
}
ret = true; /* incremented */
@@ -3569,21 +3569,21 @@ init_map: *map = 0; /* we didn't zero the page */
*/
BUG_ON(count != COUNT_CONTINUED);
while (*map == COUNT_CONTINUED) {
- kunmap_atomic(map);
+ kunmap_local(map);
page = list_next_entry(page, lru);
BUG_ON(page == head);
- map = kmap_atomic(page) + offset;
+ map = kmap_local_page(page) + offset;
}
BUG_ON(*map == 0);
*map -= 1;
if (*map == 0)
count = 0;
- kunmap_atomic(map);
+ kunmap_local(map);
while ((page = list_prev_entry(page, lru)) != head) {
- map = kmap_atomic(page) + offset;
+ map = kmap_local_page(page) + offset;
*map = SWAP_CONT_MAX | count;
count = COUNT_CONTINUED;
- kunmap_atomic(map);
+ kunmap_local(map);
}
ret = count == COUNT_CONTINUED;
}
--
2.42.0
