@@ -1929,9 +1929,8 @@ static int recompress_slot(struct zram *zram, u32 index, struct page *page,
unsigned int comp_len_new;
unsigned int class_index_old;
unsigned int class_index_new;
- u32 num_recomps = 0;
void *src, *dst;
- int ret;
+ int ret = 0;
handle_old = zram_get_handle(zram, index);
if (!handle_old)
@@ -1974,7 +1973,6 @@ static int recompress_slot(struct zram *zram, u32 index, struct page *page,
if (!zram->comps[prio])
continue;
- num_recomps++;
zstrm = zcomp_stream_get(zram->comps[prio]);
src = kmap_local_page(page);
ret = zcomp_compress(zram->comps[prio], zstrm,
@@ -1983,7 +1981,8 @@ static int recompress_slot(struct zram *zram, u32 index, struct page *page,
if (ret) {
zcomp_stream_put(zstrm);
- return ret;
+ zstrm = NULL;
+ break;
}
class_index_new = zs_lookup_class_index(zram->mem_pool,
@@ -1993,6 +1992,7 @@ static int recompress_slot(struct zram *zram, u32 index, struct page *page,
if (class_index_new >= class_index_old ||
(threshold && comp_len_new >= threshold)) {
zcomp_stream_put(zstrm);
+ zstrm = NULL;
continue;
}
@@ -2000,14 +2000,6 @@ static int recompress_slot(struct zram *zram, u32 index, struct page *page,
break;
}
- /*
- * We did not try to recompress, e.g. when we have only one
- * secondary algorithm and the page is already recompressed
- * using that algorithm
- */
- if (!zstrm)
- return 0;
-
/*
* Decrement the limit (if set) on pages we can recompress, even
* when current recompression was unsuccessful or did not compress
@@ -2017,38 +2009,31 @@ static int recompress_slot(struct zram *zram, u32 index, struct page *page,
if (*num_recomp_pages)
*num_recomp_pages -= 1;
- if (class_index_new >= class_index_old) {
+ /* Compression error */
+ if (ret)
+ return ret;
+
+ if (!zstrm) {
/*
* Secondary algorithms failed to re-compress the page
- * in a way that would save memory, mark the object as
- * incompressible so that we will not try to compress
- * it again.
+ * in a way that would save memory.
*
- * We need to make sure that all secondary algorithms have
- * failed, so we test if the number of recompressions matches
- * the number of active secondary algorithms.
+ * Mark the object incompressible if the max-priority
+ * algorithm couldn't re-compress it.
*/
- if (num_recomps == zram->num_active_comps - 1)
- zram_set_flag(zram, index, ZRAM_INCOMPRESSIBLE);
+ if (prio < zram->num_active_comps)
+ return 0;
+ zram_set_flag(zram, index, ZRAM_INCOMPRESSIBLE);
return 0;
}
- /* Successful recompression but above threshold */
- if (threshold && comp_len_new >= threshold)
- return 0;
-
/*
- * No direct reclaim (slow path) for handle allocation and no
- * re-compression attempt (unlike in zram_write_bvec()) since
- * we already have stored that object in zsmalloc. If we cannot
- * alloc memory for recompressed object then we bail out and
- * simply keep the old (existing) object in zsmalloc.
+ * We are holding per-CPU stream mutex and entry lock so better
+ * avoid direct reclaim. Allocation error is not fatal since
+ * we still have the old object in the mem_pool.
*/
handle_new = zs_malloc(zram->mem_pool, comp_len_new,
- __GFP_KSWAPD_RECLAIM |
- __GFP_NOWARN |
- __GFP_HIGHMEM |
- __GFP_MOVABLE);
+ GFP_NOWAIT | __GFP_HIGHMEM | __GFP_MOVABLE);
if (IS_ERR_VALUE(handle_new)) {
zcomp_stream_put(zstrm);
return PTR_ERR((void *)handle_new);
This reworks recompression loop handling: - set a rule that stream-put NULLs the stream pointer If the loop returns with a non-NULL stream then it's a successfull recompression, otherwise the stream should always be NULL. - do not count the number of recompressions Mark object as incompressible as soon as the algorithm with the highest priority failed to compress that object. - count compression errors as resource usage Even if compression has failed, we still need to bump num_recomp_pages counter. Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> --- drivers/block/zram/zram_drv.c | 53 +++++++++++++---------------------- 1 file changed, 19 insertions(+), 34 deletions(-)