Hi Mike,
On 2020-12-07 16:41, Mike Galbraith wrote:
On Mon, 2020-12-07 at 16:21 +0100, Vitaly Wool wrote:
On Mon, Dec 7, 2020 at 1:34 PM Mike Galbraith <efault@xxxxxx> wrote:
Unfortunately, that made zero difference.
Okay, I suggest that you submit the patch that changes read_lock() to
write_lock() in __release_z3fold_page() and I'll ack it then.
I would like to rewrite the code so that write_lock is not necessary
there but I don't want to hold you back and it isn't likely that I'll
complete this today.
Nah, I'm in no rush... especially not to sign off on "Because the
little voices in my head said this bit should look like that bit over
yonder, and testing _seems_ to indicate they're right about that" :)
-Mike
okay, thanks. Would this make things better:
diff --git a/mm/z3fold.c b/mm/z3fold.c
index 18feaa0bc537..340c38a5ffac 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -303,10 +303,9 @@ static inline void put_z3fold_header(struct
z3fold_header *zhdr)
z3fold_page_unlock(zhdr);
}
-static inline void free_handle(unsigned long handle)
+static inline void free_handle(unsigned long handle, struct
z3fold_header *zhdr)
{
struct z3fold_buddy_slots *slots;
- struct z3fold_header *zhdr;
int i;
bool is_free;
@@ -316,22 +315,13 @@ static inline void free_handle(unsigned long handle)
if (WARN_ON(*(unsigned long *)handle == 0))
return;
- zhdr = handle_to_z3fold_header(handle);
slots = handle_to_slots(handle);
write_lock(&slots->lock);
*(unsigned long *)handle = 0;
- if (zhdr->slots == slots) {
- write_unlock(&slots->lock);
- return; /* simple case, nothing else to do */
- }
+ if (zhdr->slots != slots)
+ zhdr->foreign_handles--;
- /* we are freeing a foreign handle if we are here */
- zhdr->foreign_handles--;
is_free = true;
- if (!test_bit(HANDLES_ORPHANED, &slots->pool)) {
- write_unlock(&slots->lock);
- return;
- }
for (i = 0; i <= BUDDY_MASK; i++) {
if (slots->slot[i]) {
is_free = false;
@@ -343,6 +333,8 @@ static inline void free_handle(unsigned long handle)
if (is_free) {
struct z3fold_pool *pool = slots_to_pool(slots);
+ if (zhdr->slots == slots)
+ zhdr->slots = NULL;
kmem_cache_free(pool->c_handle, slots);
}
}
@@ -525,8 +517,6 @@ static void __release_z3fold_page(struct
z3fold_header *zhdr, bool locked)
{
struct page *page = virt_to_page(zhdr);
struct z3fold_pool *pool = zhdr_to_pool(zhdr);
- bool is_free = true;
- int i;
WARN_ON(!list_empty(&zhdr->buddy));
set_bit(PAGE_STALE, &page->private);
@@ -536,21 +526,6 @@ static void __release_z3fold_page(struct
z3fold_header *zhdr, bool locked)
list_del_init(&page->lru);
spin_unlock(&pool->lock);
- /* If there are no foreign handles, free the handles array */
- read_lock(&zhdr->slots->lock);
- for (i = 0; i <= BUDDY_MASK; i++) {
- if (zhdr->slots->slot[i]) {
- is_free = false;
- break;
- }
- }
- if (!is_free)
- set_bit(HANDLES_ORPHANED, &zhdr->slots->pool);
- read_unlock(&zhdr->slots->lock);
-
- if (is_free)
- kmem_cache_free(pool->c_handle, zhdr->slots);
-
if (locked)
z3fold_page_unlock(zhdr);
@@ -973,6 +948,9 @@ static inline struct z3fold_header
*__z3fold_alloc(struct z3fold_pool *pool,
}
}
+ if (zhdr && !zhdr->slots)
+ zhdr->slots = alloc_slots(pool,
+ can_sleep ? GFP_NOIO : GFP_ATOMIC);
return zhdr;
}
@@ -1270,7 +1248,7 @@ static void z3fold_free(struct z3fold_pool *pool,
unsigned long handle)
}
if (!page_claimed)
- free_handle(handle);
+ free_handle(handle, zhdr);
if (kref_put(&zhdr->refcount, release_z3fold_page_locked_list)) {
atomic64_dec(&pool->pages_nr);
return;
@@ -1429,19 +1407,19 @@ static int z3fold_reclaim_page(struct
z3fold_pool *pool, unsigned int retries)
ret = pool->ops->evict(pool, middle_handle);
if (ret)
goto next;
- free_handle(middle_handle);
+ free_handle(middle_handle, zhdr);
}
if (first_handle) {
ret = pool->ops->evict(pool, first_handle);
if (ret)
goto next;
- free_handle(first_handle);
+ free_handle(first_handle, zhdr);
}
if (last_handle) {
ret = pool->ops->evict(pool, last_handle);
if (ret)
goto next;
- free_handle(last_handle);
+ free_handle(last_handle, zhdr);
}
next:
if (test_bit(PAGE_HEADLESS, &page->private)) {
--
Best regards,
Vitaly
