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[PATCH v2 3/3] bcache: Remove unnecessary select MIN_HEAP

by Kuan-Wei Chiu

After reverting the transition to the generic min heap library, bcache no longer depends on MIN_HEAP. The select entry can be removed to reduce code size and shrink the kernel's attack surface. This change effectively reverts the bcache-related part of commit 92a8b224b833 ("lib/min_heap: introduce non-inline versions of min heap API functions"). This is part of a series of changes to address a performance regression caused by the use of the generic min_heap implementation. As reported by Robert, bcache now suffers from latency spikes, with P100 (max) latency increasing from 600 ms to 2.4 seconds every 5 minutes. These regressions degrade bcache's effectiveness as a low-latency cache layer and lead to frequent timeouts and application stalls in production environments. Link: https://lore.kernel.org/lkml/CAJhEC05+0S69z+3+FB2Cd0hD+pCRyWTKLEOsc8BOmH73p… Fixes: 866898efbb25 ("bcache: remove heap-related macros and switch to generic min_heap") Fixes: 92a8b224b833 ("lib/min_heap: introduce non-inline versions of min heap API functions") Reported-by: Robert Pang <robertpang(a)google.com> Closes: https://lore.kernel.org/linux-bcache/CAJhEC06F_AtrPgw2-7CvCqZgeStgCtitbD-ry… Cc: stable(a)vger.kernel.org Signed-off-by: Kuan-Wei Chiu <visitorckw(a)gmail.com> --- drivers/md/bcache/Kconfig | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/md/bcache/Kconfig b/drivers/md/bcache/Kconfig index d4697e79d5a3..b2d10063d35f 100644 --- a/drivers/md/bcache/Kconfig +++ b/drivers/md/bcache/Kconfig @@ -5,7 +5,6 @@ config BCACHE select BLOCK_HOLDER_DEPRECATED if SYSFS select CRC64 select CLOSURES - select MIN_HEAP help Allows a block device to be used as cache for other devices; uses a btree for indexing and the layout is optimized for SSDs. -- 2.34.1

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[PATCH v2 2/3] Revert "bcache: remove heap-related macros and switch to generic min_heap"

by Kuan-Wei Chiu

This reverts commit 866898efbb25bb44fd42848318e46db9e785973a. The generic bottom-up min_heap implementation causes performance regression in invalidate_buckets_lru(), a hot path in bcache. Before the cache is fully populated, new_bucket_prio() often returns zero, leading to many equal comparisons. In such cases, bottom-up sift_down performs up to 2 * log2(n) comparisons, while the original top-down approach completes with just O() comparisons, resulting in a measurable performance gap. The performance degradation is further worsened by the non-inlined min_heap API functions introduced in commit 92a8b224b833 ("lib/min_heap: introduce non-inline versions of min heap API functions"), adding function call overhead to this critical path. As reported by Robert, bcache now suffers from latency spikes, with P100 (max) latency increasing from 600 ms to 2.4 seconds every 5 minutes. These regressions degrade bcache's effectiveness as a low-latency cache layer and lead to frequent timeouts and application stalls in production environments. This revert aims to restore bcache's original low-latency behavior. Link: https://lore.kernel.org/lkml/CAJhEC05+0S69z+3+FB2Cd0hD+pCRyWTKLEOsc8BOmH73p… Fixes: 866898efbb25 ("bcache: remove heap-related macros and switch to generic min_heap") Fixes: 92a8b224b833 ("lib/min_heap: introduce non-inline versions of min heap API functions") Reported-by: Robert Pang <robertpang(a)google.com> Closes: https://lore.kernel.org/linux-bcache/CAJhEC06F_AtrPgw2-7CvCqZgeStgCtitbD-ry… Cc: stable(a)vger.kernel.org Signed-off-by: Kuan-Wei Chiu <visitorckw(a)gmail.com> --- drivers/md/bcache/alloc.c | 64 +++++------------- drivers/md/bcache/bcache.h | 2 +- drivers/md/bcache/bset.c | 124 ++++++++++++---------------------- drivers/md/bcache/bset.h | 40 ++++++----- drivers/md/bcache/btree.c | 69 ++++++++----------- drivers/md/bcache/extents.c | 53 ++++++--------- drivers/md/bcache/movinggc.c | 41 +++-------- drivers/md/bcache/super.c | 3 +- drivers/md/bcache/sysfs.c | 4 +- drivers/md/bcache/util.h | 67 +++++++++++++++++- drivers/md/bcache/writeback.c | 13 ++-- 11 files changed, 217 insertions(+), 263 deletions(-) diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c index da50f6661bae..48ce750bf70a 100644 --- a/drivers/md/bcache/alloc.c +++ b/drivers/md/bcache/alloc.c @@ -164,68 +164,40 @@ static void bch_invalidate_one_bucket(struct cache *ca, struct bucket *b) * prio is worth 1/8th of what INITIAL_PRIO is worth. */ -static inline unsigned int new_bucket_prio(struct cache *ca, struct bucket *b) -{ - unsigned int min_prio = (INITIAL_PRIO - ca->set->min_prio) / 8; - - return (b->prio - ca->set->min_prio + min_prio) * GC_SECTORS_USED(b); -} - -static inline bool new_bucket_max_cmp(const void *l, const void *r, void *args) -{ - struct bucket **lhs = (struct bucket **)l; - struct bucket **rhs = (struct bucket **)r; - struct cache *ca = args; - - return new_bucket_prio(ca, *lhs) > new_bucket_prio(ca, *rhs); -} - -static inline bool new_bucket_min_cmp(const void *l, const void *r, void *args) -{ - struct bucket **lhs = (struct bucket **)l; - struct bucket **rhs = (struct bucket **)r; - struct cache *ca = args; - - return new_bucket_prio(ca, *lhs) < new_bucket_prio(ca, *rhs); -} - -static inline void new_bucket_swap(void *l, void *r, void __always_unused *args) -{ - struct bucket **lhs = l, **rhs = r; +#define bucket_prio(b) \ +({ \ + unsigned int min_prio = (INITIAL_PRIO - ca->set->min_prio) / 8; \ + \ + (b->prio - ca->set->min_prio + min_prio) * GC_SECTORS_USED(b); \ +}) - swap(*lhs, *rhs); -} +#define bucket_max_cmp(l, r) (bucket_prio(l) < bucket_prio(r)) +#define bucket_min_cmp(l, r) (bucket_prio(l) > bucket_prio(r)) static void invalidate_buckets_lru(struct cache *ca) { struct bucket *b; - const struct min_heap_callbacks bucket_max_cmp_callback = { - .less = new_bucket_max_cmp, - .swp = new_bucket_swap, - }; - const struct min_heap_callbacks bucket_min_cmp_callback = { - .less = new_bucket_min_cmp, - .swp = new_bucket_swap, - }; + ssize_t i; - ca->heap.nr = 0; + ca->heap.used = 0; for_each_bucket(b, ca) { if (!bch_can_invalidate_bucket(ca, b)) continue; - if (!min_heap_full(&ca->heap)) - min_heap_push(&ca->heap, &b, &bucket_max_cmp_callback, ca); - else if (!new_bucket_max_cmp(&b, min_heap_peek(&ca->heap), ca)) { + if (!heap_full(&ca->heap)) + heap_add(&ca->heap, b, bucket_max_cmp); + else if (bucket_max_cmp(b, heap_peek(&ca->heap))) { ca->heap.data[0] = b; - min_heap_sift_down(&ca->heap, 0, &bucket_max_cmp_callback, ca); + heap_sift(&ca->heap, 0, bucket_max_cmp); } } - min_heapify_all(&ca->heap, &bucket_min_cmp_callback, ca); + for (i = ca->heap.used / 2 - 1; i >= 0; --i) + heap_sift(&ca->heap, i, bucket_min_cmp); while (!fifo_full(&ca->free_inc)) { - if (!ca->heap.nr) { + if (!heap_pop(&ca->heap, b, bucket_min_cmp)) { /* * We don't want to be calling invalidate_buckets() * multiple times when it can't do anything @@ -234,8 +206,6 @@ static void invalidate_buckets_lru(struct cache *ca) wake_up_gc(ca->set); return; } - b = min_heap_peek(&ca->heap)[0]; - min_heap_pop(&ca->heap, &bucket_min_cmp_callback, ca); bch_invalidate_one_bucket(ca, b); } diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h index 785b0d9008fa..1d33e40d26ea 100644 --- a/drivers/md/bcache/bcache.h +++ b/drivers/md/bcache/bcache.h @@ -458,7 +458,7 @@ struct cache { /* Allocation stuff: */ struct bucket *buckets; - DEFINE_MIN_HEAP(struct bucket *, cache_heap) heap; + DECLARE_HEAP(struct bucket *, heap); /* * If nonzero, we know we aren't going to find any buckets to invalidate diff --git a/drivers/md/bcache/bset.c b/drivers/md/bcache/bset.c index bd97d8626887..463eb13bd0b2 100644 --- a/drivers/md/bcache/bset.c +++ b/drivers/md/bcache/bset.c @@ -54,11 +54,9 @@ void bch_dump_bucket(struct btree_keys *b) int __bch_count_data(struct btree_keys *b) { unsigned int ret = 0; - struct btree_iter iter; + struct btree_iter_stack iter; struct bkey *k; - min_heap_init(&iter.heap, NULL, MAX_BSETS); - if (b->ops->is_extents) for_each_key(b, k, &iter) ret += KEY_SIZE(k); @@ -69,11 +67,9 @@ void __bch_check_keys(struct btree_keys *b, const char *fmt, ...) { va_list args; struct bkey *k, *p = NULL; - struct btree_iter iter; + struct btree_iter_stack iter; const char *err; - min_heap_init(&iter.heap, NULL, MAX_BSETS); - for_each_key(b, k, &iter) { if (b->ops->is_extents) { err = "Keys out of order"; @@ -114,9 +110,9 @@ void __bch_check_keys(struct btree_keys *b, const char *fmt, ...) static void bch_btree_iter_next_check(struct btree_iter *iter) { - struct bkey *k = iter->heap.data->k, *next = bkey_next(k); + struct bkey *k = iter->data->k, *next = bkey_next(k); - if (next < iter->heap.data->end && + if (next < iter->data->end && bkey_cmp(k, iter->b->ops->is_extents ? &START_KEY(next) : next) > 0) { bch_dump_bucket(iter->b); @@ -883,14 +879,12 @@ unsigned int bch_btree_insert_key(struct btree_keys *b, struct bkey *k, unsigned int status = BTREE_INSERT_STATUS_NO_INSERT; struct bset *i = bset_tree_last(b)->data; struct bkey *m, *prev = NULL; - struct btree_iter iter; + struct btree_iter_stack iter; struct bkey preceding_key_on_stack = ZERO_KEY; struct bkey *preceding_key_p = &preceding_key_on_stack; BUG_ON(b->ops->is_extents && !KEY_SIZE(k)); - min_heap_init(&iter.heap, NULL, MAX_BSETS); - /* * If k has preceding key, preceding_key_p will be set to address * of k's preceding key; otherwise preceding_key_p will be set @@ -901,9 +895,9 @@ unsigned int bch_btree_insert_key(struct btree_keys *b, struct bkey *k, else preceding_key(k, &preceding_key_p); - m = bch_btree_iter_init(b, &iter, preceding_key_p); + m = bch_btree_iter_stack_init(b, &iter, preceding_key_p); - if (b->ops->insert_fixup(b, k, &iter, replace_key)) + if (b->ops->insert_fixup(b, k, &iter.iter, replace_key)) return status; status = BTREE_INSERT_STATUS_INSERT; @@ -1083,102 +1077,79 @@ struct bkey *__bch_bset_search(struct btree_keys *b, struct bset_tree *t, /* Btree iterator */ -typedef bool (new_btree_iter_cmp_fn)(const void *, const void *, void *); - -static inline bool new_btree_iter_cmp(const void *l, const void *r, void __always_unused *args) -{ - const struct btree_iter_set *_l = l; - const struct btree_iter_set *_r = r; - - return bkey_cmp(_l->k, _r->k) <= 0; -} +typedef bool (btree_iter_cmp_fn)(struct btree_iter_set, + struct btree_iter_set); -static inline void new_btree_iter_swap(void *iter1, void *iter2, void __always_unused *args) +static inline bool btree_iter_cmp(struct btree_iter_set l, + struct btree_iter_set r) { - struct btree_iter_set *_iter1 = iter1; - struct btree_iter_set *_iter2 = iter2; - - swap(*_iter1, *_iter2); + return bkey_cmp(l.k, r.k) > 0; } static inline bool btree_iter_end(struct btree_iter *iter) { - return !iter->heap.nr; + return !iter->used; } void bch_btree_iter_push(struct btree_iter *iter, struct bkey *k, struct bkey *end) { - const struct min_heap_callbacks callbacks = { - .less = new_btree_iter_cmp, - .swp = new_btree_iter_swap, - }; - if (k != end) - BUG_ON(!min_heap_push(&iter->heap, - &((struct btree_iter_set) { k, end }), - &callbacks, - NULL)); + BUG_ON(!heap_add(iter, + ((struct btree_iter_set) { k, end }), + btree_iter_cmp)); } -static struct bkey *__bch_btree_iter_init(struct btree_keys *b, - struct btree_iter *iter, - struct bkey *search, - struct bset_tree *start) +static struct bkey *__bch_btree_iter_stack_init(struct btree_keys *b, + struct btree_iter_stack *iter, + struct bkey *search, + struct bset_tree *start) { struct bkey *ret = NULL; - iter->heap.size = ARRAY_SIZE(iter->heap.preallocated); - iter->heap.nr = 0; + iter->iter.size = ARRAY_SIZE(iter->stack_data); + iter->iter.used = 0; #ifdef CONFIG_BCACHE_DEBUG - iter->b = b; + iter->iter.b = b; #endif for (; start <= bset_tree_last(b); start++) { ret = bch_bset_search(b, start, search); - bch_btree_iter_push(iter, ret, bset_bkey_last(start->data)); + bch_btree_iter_push(&iter->iter, ret, bset_bkey_last(start->data)); } return ret; } -struct bkey *bch_btree_iter_init(struct btree_keys *b, - struct btree_iter *iter, +struct bkey *bch_btree_iter_stack_init(struct btree_keys *b, + struct btree_iter_stack *iter, struct bkey *search) { - return __bch_btree_iter_init(b, iter, search, b->set); + return __bch_btree_iter_stack_init(b, iter, search, b->set); } static inline struct bkey *__bch_btree_iter_next(struct btree_iter *iter, - new_btree_iter_cmp_fn *cmp) + btree_iter_cmp_fn *cmp) { struct btree_iter_set b __maybe_unused; struct bkey *ret = NULL; - const struct min_heap_callbacks callbacks = { - .less = cmp, - .swp = new_btree_iter_swap, - }; if (!btree_iter_end(iter)) { bch_btree_iter_next_check(iter); - ret = iter->heap.data->k; - iter->heap.data->k = bkey_next(iter->heap.data->k); + ret = iter->data->k; + iter->data->k = bkey_next(iter->data->k); - if (iter->heap.data->k > iter->heap.data->end) { + if (iter->data->k > iter->data->end) { WARN_ONCE(1, "bset was corrupt!\n"); - iter->heap.data->k = iter->heap.data->end; + iter->data->k = iter->data->end; } - if (iter->heap.data->k == iter->heap.data->end) { - if (iter->heap.nr) { - b = min_heap_peek(&iter->heap)[0]; - min_heap_pop(&iter->heap, &callbacks, NULL); - } - } + if (iter->data->k == iter->data->end) + heap_pop(iter, b, cmp); else - min_heap_sift_down(&iter->heap, 0, &callbacks, NULL); + heap_sift(iter, 0, cmp); } return ret; @@ -1186,7 +1157,7 @@ static inline struct bkey *__bch_btree_iter_next(struct btree_iter *iter, struct bkey *bch_btree_iter_next(struct btree_iter *iter) { - return __bch_btree_iter_next(iter, new_btree_iter_cmp); + return __bch_btree_iter_next(iter, btree_iter_cmp); } @@ -1224,18 +1195,16 @@ static void btree_mergesort(struct btree_keys *b, struct bset *out, struct btree_iter *iter, bool fixup, bool remove_stale) { + int i; struct bkey *k, *last = NULL; BKEY_PADDED(k) tmp; bool (*bad)(struct btree_keys *, const struct bkey *) = remove_stale ? bch_ptr_bad : bch_ptr_invalid; - const struct min_heap_callbacks callbacks = { - .less = b->ops->sort_cmp, - .swp = new_btree_iter_swap, - }; /* Heapify the iterator, using our comparison function */ - min_heapify_all(&iter->heap, &callbacks, NULL); + for (i = iter->used / 2 - 1; i >= 0; --i) + heap_sift(iter, i, b->ops->sort_cmp); while (!btree_iter_end(iter)) { if (b->ops->sort_fixup && fixup) @@ -1324,11 +1293,10 @@ void bch_btree_sort_partial(struct btree_keys *b, unsigned int start, struct bset_sort_state *state) { size_t order = b->page_order, keys = 0; - struct btree_iter iter; + struct btree_iter_stack iter; int oldsize = bch_count_data(b); - min_heap_init(&iter.heap, NULL, MAX_BSETS); - __bch_btree_iter_init(b, &iter, NULL, &b->set[start]); + __bch_btree_iter_stack_init(b, &iter, NULL, &b->set[start]); if (start) { unsigned int i; @@ -1339,7 +1307,7 @@ void bch_btree_sort_partial(struct btree_keys *b, unsigned int start, order = get_order(__set_bytes(b->set->data, keys)); } - __btree_sort(b, &iter, start, order, false, state); + __btree_sort(b, &iter.iter, start, order, false, state); EBUG_ON(oldsize >= 0 && bch_count_data(b) != oldsize); } @@ -1355,13 +1323,11 @@ void bch_btree_sort_into(struct btree_keys *b, struct btree_keys *new, struct bset_sort_state *state) { uint64_t start_time = local_clock(); - struct btree_iter iter; - - min_heap_init(&iter.heap, NULL, MAX_BSETS); + struct btree_iter_stack iter; - bch_btree_iter_init(b, &iter, NULL); + bch_btree_iter_stack_init(b, &iter, NULL); - btree_mergesort(b, new->set->data, &iter, false, true); + btree_mergesort(b, new->set->data, &iter.iter, false, true); bch_time_stats_update(&state->time, start_time); diff --git a/drivers/md/bcache/bset.h b/drivers/md/bcache/bset.h index f79441acd4c1..011f6062c4c0 100644 --- a/drivers/md/bcache/bset.h +++ b/drivers/md/bcache/bset.h @@ -187,9 +187,8 @@ struct bset_tree { }; struct btree_keys_ops { - bool (*sort_cmp)(const void *l, - const void *r, - void *args); + bool (*sort_cmp)(struct btree_iter_set l, + struct btree_iter_set r); struct bkey *(*sort_fixup)(struct btree_iter *iter, struct bkey *tmp); bool (*insert_fixup)(struct btree_keys *b, @@ -313,17 +312,23 @@ enum { BTREE_INSERT_STATUS_FRONT_MERGE, }; -struct btree_iter_set { - struct bkey *k, *end; -}; - /* Btree key iteration */ struct btree_iter { + size_t size, used; #ifdef CONFIG_BCACHE_DEBUG struct btree_keys *b; #endif - MIN_HEAP_PREALLOCATED(struct btree_iter_set, btree_iter_heap, MAX_BSETS) heap; + struct btree_iter_set { + struct bkey *k, *end; + } data[]; +}; + +/* Fixed-size btree_iter that can be allocated on the stack */ + +struct btree_iter_stack { + struct btree_iter iter; + struct btree_iter_set stack_data[MAX_BSETS]; }; typedef bool (*ptr_filter_fn)(struct btree_keys *b, const struct bkey *k); @@ -335,9 +340,9 @@ struct bkey *bch_btree_iter_next_filter(struct btree_iter *iter, void bch_btree_iter_push(struct btree_iter *iter, struct bkey *k, struct bkey *end); -struct bkey *bch_btree_iter_init(struct btree_keys *b, - struct btree_iter *iter, - struct bkey *search); +struct bkey *bch_btree_iter_stack_init(struct btree_keys *b, + struct btree_iter_stack *iter, + struct bkey *search); struct bkey *__bch_bset_search(struct btree_keys *b, struct bset_tree *t, const struct bkey *search); @@ -352,13 +357,14 @@ static inline struct bkey *bch_bset_search(struct btree_keys *b, return search ? __bch_bset_search(b, t, search) : t->data->start; } -#define for_each_key_filter(b, k, iter, filter) \ - for (bch_btree_iter_init((b), (iter), NULL); \ - ((k) = bch_btree_iter_next_filter((iter), (b), filter));) +#define for_each_key_filter(b, k, stack_iter, filter) \ + for (bch_btree_iter_stack_init((b), (stack_iter), NULL); \ + ((k) = bch_btree_iter_next_filter(&((stack_iter)->iter), (b), \ + filter));) -#define for_each_key(b, k, iter) \ - for (bch_btree_iter_init((b), (iter), NULL); \ - ((k) = bch_btree_iter_next(iter));) +#define for_each_key(b, k, stack_iter) \ + for (bch_btree_iter_stack_init((b), (stack_iter), NULL); \ + ((k) = bch_btree_iter_next(&((stack_iter)->iter)));) /* Sorting */ diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c index 1d0100677357..210b59007d98 100644 --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -148,19 +148,19 @@ void bch_btree_node_read_done(struct btree *b) { const char *err = "bad btree header"; struct bset *i = btree_bset_first(b); - struct btree_iter iter; + struct btree_iter *iter; /* * c->fill_iter can allocate an iterator with more memory space * than static MAX_BSETS. * See the comment arount cache_set->fill_iter. */ - iter.heap.data = mempool_alloc(&b->c->fill_iter, GFP_NOIO); - iter.heap.size = b->c->cache->sb.bucket_size / b->c->cache->sb.block_size; - iter.heap.nr = 0; + iter = mempool_alloc(&b->c->fill_iter, GFP_NOIO); + iter->size = b->c->cache->sb.bucket_size / b->c->cache->sb.block_size; + iter->used = 0; #ifdef CONFIG_BCACHE_DEBUG - iter.b = &b->keys; + iter->b = &b->keys; #endif if (!i->seq) @@ -198,7 +198,7 @@ void bch_btree_node_read_done(struct btree *b) if (i != b->keys.set[0].data && !i->keys) goto err; - bch_btree_iter_push(&iter, i->start, bset_bkey_last(i)); + bch_btree_iter_push(iter, i->start, bset_bkey_last(i)); b->written += set_blocks(i, block_bytes(b->c->cache)); } @@ -210,7 +210,7 @@ void bch_btree_node_read_done(struct btree *b) if (i->seq == b->keys.set[0].data->seq) goto err; - bch_btree_sort_and_fix_extents(&b->keys, &iter, &b->c->sort); + bch_btree_sort_and_fix_extents(&b->keys, iter, &b->c->sort); i = b->keys.set[0].data; err = "short btree key"; @@ -222,7 +222,7 @@ void bch_btree_node_read_done(struct btree *b) bch_bset_init_next(&b->keys, write_block(b), bset_magic(&b->c->cache->sb)); out: - mempool_free(iter.heap.data, &b->c->fill_iter); + mempool_free(iter, &b->c->fill_iter); return; err: set_btree_node_io_error(b); @@ -1306,11 +1306,9 @@ static bool btree_gc_mark_node(struct btree *b, struct gc_stat *gc) uint8_t stale = 0; unsigned int keys = 0, good_keys = 0; struct bkey *k; - struct btree_iter iter; + struct btree_iter_stack iter; struct bset_tree *t; - min_heap_init(&iter.heap, NULL, MAX_BSETS); - gc->nodes++; for_each_key_filter(&b->keys, k, &iter, bch_ptr_invalid) { @@ -1569,11 +1567,9 @@ static int btree_gc_rewrite_node(struct btree *b, struct btree_op *op, static unsigned int btree_gc_count_keys(struct btree *b) { struct bkey *k; - struct btree_iter iter; + struct btree_iter_stack iter; unsigned int ret = 0; - min_heap_init(&iter.heap, NULL, MAX_BSETS); - for_each_key_filter(&b->keys, k, &iter, bch_ptr_bad) ret += bkey_u64s(k); @@ -1612,18 +1608,18 @@ static int btree_gc_recurse(struct btree *b, struct btree_op *op, int ret = 0; bool should_rewrite; struct bkey *k; - struct btree_iter iter; + struct btree_iter_stack iter; struct gc_merge_info r[GC_MERGE_NODES]; struct gc_merge_info *i, *last = r + ARRAY_SIZE(r) - 1; - min_heap_init(&iter.heap, NULL, MAX_BSETS); - bch_btree_iter_init(&b->keys, &iter, &b->c->gc_done); + bch_btree_iter_stack_init(&b->keys, &iter, &b->c->gc_done); for (i = r; i < r + ARRAY_SIZE(r); i++) i->b = ERR_PTR(-EINTR); while (1) { - k = bch_btree_iter_next_filter(&iter, &b->keys, bch_ptr_bad); + k = bch_btree_iter_next_filter(&iter.iter, &b->keys, + bch_ptr_bad); if (k) { r->b = bch_btree_node_get(b->c, op, k, b->level - 1, true, b); @@ -1918,9 +1914,7 @@ static int bch_btree_check_recurse(struct btree *b, struct btree_op *op) { int ret = 0; struct bkey *k, *p = NULL; - struct btree_iter iter; - - min_heap_init(&iter.heap, NULL, MAX_BSETS); + struct btree_iter_stack iter; for_each_key_filter(&b->keys, k, &iter, bch_ptr_invalid) bch_initial_mark_key(b->c, b->level, k); @@ -1928,10 +1922,10 @@ static int bch_btree_check_recurse(struct btree *b, struct btree_op *op) bch_initial_mark_key(b->c, b->level + 1, &b->key); if (b->level) { - bch_btree_iter_init(&b->keys, &iter, NULL); + bch_btree_iter_stack_init(&b->keys, &iter, NULL); do { - k = bch_btree_iter_next_filter(&iter, &b->keys, + k = bch_btree_iter_next_filter(&iter.iter, &b->keys, bch_ptr_bad); if (k) { btree_node_prefetch(b, k); @@ -1959,7 +1953,7 @@ static int bch_btree_check_thread(void *arg) struct btree_check_info *info = arg; struct btree_check_state *check_state = info->state; struct cache_set *c = check_state->c; - struct btree_iter iter; + struct btree_iter_stack iter; struct bkey *k, *p; int cur_idx, prev_idx, skip_nr; @@ -1967,11 +1961,9 @@ static int bch_btree_check_thread(void *arg) cur_idx = prev_idx = 0; ret = 0; - min_heap_init(&iter.heap, NULL, MAX_BSETS); - /* root node keys are checked before thread created */ - bch_btree_iter_init(&c->root->keys, &iter, NULL); - k = bch_btree_iter_next_filter(&iter, &c->root->keys, bch_ptr_bad); + bch_btree_iter_stack_init(&c->root->keys, &iter, NULL); + k = bch_btree_iter_next_filter(&iter.iter, &c->root->keys, bch_ptr_bad); BUG_ON(!k); p = k; @@ -1989,7 +1981,7 @@ static int bch_btree_check_thread(void *arg) skip_nr = cur_idx - prev_idx; while (skip_nr) { - k = bch_btree_iter_next_filter(&iter, + k = bch_btree_iter_next_filter(&iter.iter, &c->root->keys, bch_ptr_bad); if (k) @@ -2062,11 +2054,9 @@ int bch_btree_check(struct cache_set *c) int ret = 0; int i; struct bkey *k = NULL; - struct btree_iter iter; + struct btree_iter_stack iter; struct btree_check_state check_state; - min_heap_init(&iter.heap, NULL, MAX_BSETS); - /* check and mark root node keys */ for_each_key_filter(&c->root->keys, k, &iter, bch_ptr_invalid) bch_initial_mark_key(c, c->root->level, k); @@ -2560,12 +2550,11 @@ static int bch_btree_map_nodes_recurse(struct btree *b, struct btree_op *op, if (b->level) { struct bkey *k; - struct btree_iter iter; + struct btree_iter_stack iter; - min_heap_init(&iter.heap, NULL, MAX_BSETS); - bch_btree_iter_init(&b->keys, &iter, from); + bch_btree_iter_stack_init(&b->keys, &iter, from); - while ((k = bch_btree_iter_next_filter(&iter, &b->keys, + while ((k = bch_btree_iter_next_filter(&iter.iter, &b->keys, bch_ptr_bad))) { ret = bcache_btree(map_nodes_recurse, k, b, op, from, fn, flags); @@ -2594,12 +2583,12 @@ int bch_btree_map_keys_recurse(struct btree *b, struct btree_op *op, { int ret = MAP_CONTINUE; struct bkey *k; - struct btree_iter iter; + struct btree_iter_stack iter; - min_heap_init(&iter.heap, NULL, MAX_BSETS); - bch_btree_iter_init(&b->keys, &iter, from); + bch_btree_iter_stack_init(&b->keys, &iter, from); - while ((k = bch_btree_iter_next_filter(&iter, &b->keys, bch_ptr_bad))) { + while ((k = bch_btree_iter_next_filter(&iter.iter, &b->keys, + bch_ptr_bad))) { ret = !b->level ? fn(op, b, k) : bcache_btree(map_keys_recurse, k, diff --git a/drivers/md/bcache/extents.c b/drivers/md/bcache/extents.c index a7221e5dbe81..d626ffcbecb9 100644 --- a/drivers/md/bcache/extents.c +++ b/drivers/md/bcache/extents.c @@ -33,16 +33,15 @@ static void sort_key_next(struct btree_iter *iter, i->k = bkey_next(i->k); if (i->k == i->end) - *i = iter->heap.data[--iter->heap.nr]; + *i = iter->data[--iter->used]; } -static bool new_bch_key_sort_cmp(const void *l, const void *r, void *args) +static bool bch_key_sort_cmp(struct btree_iter_set l, + struct btree_iter_set r) { - struct btree_iter_set *_l = (struct btree_iter_set *)l; - struct btree_iter_set *_r = (struct btree_iter_set *)r; - int64_t c = bkey_cmp(_l->k, _r->k); + int64_t c = bkey_cmp(l.k, r.k); - return !(c ? c > 0 : _l->k < _r->k); + return c ? c > 0 : l.k < r.k; } static bool __ptr_invalid(struct cache_set *c, const struct bkey *k) @@ -239,7 +238,7 @@ static bool bch_btree_ptr_insert_fixup(struct btree_keys *bk, } const struct btree_keys_ops bch_btree_keys_ops = { - .sort_cmp = new_bch_key_sort_cmp, + .sort_cmp = bch_key_sort_cmp, .insert_fixup = bch_btree_ptr_insert_fixup, .key_invalid = bch_btree_ptr_invalid, .key_bad = bch_btree_ptr_bad, @@ -256,36 +255,22 @@ const struct btree_keys_ops bch_btree_keys_ops = { * Necessary for btree_sort_fixup() - if there are multiple keys that compare * equal in different sets, we have to process them newest to oldest. */ - -static bool new_bch_extent_sort_cmp(const void *l, const void *r, void __always_unused *args) -{ - struct btree_iter_set *_l = (struct btree_iter_set *)l; - struct btree_iter_set *_r = (struct btree_iter_set *)r; - int64_t c = bkey_cmp(&START_KEY(_l->k), &START_KEY(_r->k)); - - return !(c ? c > 0 : _l->k < _r->k); -} - -static inline void new_btree_iter_swap(void *iter1, void *iter2, void __always_unused *args) +static bool bch_extent_sort_cmp(struct btree_iter_set l, + struct btree_iter_set r) { - struct btree_iter_set *_iter1 = iter1; - struct btree_iter_set *_iter2 = iter2; + int64_t c = bkey_cmp(&START_KEY(l.k), &START_KEY(r.k)); - swap(*_iter1, *_iter2); + return c ? c > 0 : l.k < r.k; } static struct bkey *bch_extent_sort_fixup(struct btree_iter *iter, struct bkey *tmp) { - const struct min_heap_callbacks callbacks = { - .less = new_bch_extent_sort_cmp, - .swp = new_btree_iter_swap, - }; - while (iter->heap.nr > 1) { - struct btree_iter_set *top = iter->heap.data, *i = top + 1; - - if (iter->heap.nr > 2 && - !new_bch_extent_sort_cmp(&i[0], &i[1], NULL)) + while (iter->used > 1) { + struct btree_iter_set *top = iter->data, *i = top + 1; + + if (iter->used > 2 && + bch_extent_sort_cmp(i[0], i[1])) i++; if (bkey_cmp(top->k, &START_KEY(i->k)) <= 0) @@ -293,7 +278,7 @@ static struct bkey *bch_extent_sort_fixup(struct btree_iter *iter, if (!KEY_SIZE(i->k)) { sort_key_next(iter, i); - min_heap_sift_down(&iter->heap, i - top, &callbacks, NULL); + heap_sift(iter, i - top, bch_extent_sort_cmp); continue; } @@ -303,7 +288,7 @@ static struct bkey *bch_extent_sort_fixup(struct btree_iter *iter, else bch_cut_front(top->k, i->k); - min_heap_sift_down(&iter->heap, i - top, &callbacks, NULL); + heap_sift(iter, i - top, bch_extent_sort_cmp); } else { /* can't happen because of comparison func */ BUG_ON(!bkey_cmp(&START_KEY(top->k), &START_KEY(i->k))); @@ -313,7 +298,7 @@ static struct bkey *bch_extent_sort_fixup(struct btree_iter *iter, bch_cut_back(&START_KEY(i->k), tmp); bch_cut_front(i->k, top->k); - min_heap_sift_down(&iter->heap, 0, &callbacks, NULL); + heap_sift(iter, 0, bch_extent_sort_cmp); return tmp; } else { @@ -633,7 +618,7 @@ static bool bch_extent_merge(struct btree_keys *bk, } const struct btree_keys_ops bch_extent_keys_ops = { - .sort_cmp = new_bch_extent_sort_cmp, + .sort_cmp = bch_extent_sort_cmp, .sort_fixup = bch_extent_sort_fixup, .insert_fixup = bch_extent_insert_fixup, .key_invalid = bch_extent_invalid, diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c index d6c73dd8eb2b..26a6a535ec32 100644 --- a/drivers/md/bcache/movinggc.c +++ b/drivers/md/bcache/movinggc.c @@ -182,27 +182,16 @@ err: if (!IS_ERR_OR_NULL(w->private)) closure_sync(&cl); } -static bool new_bucket_cmp(const void *l, const void *r, void __always_unused *args) +static bool bucket_cmp(struct bucket *l, struct bucket *r) { - struct bucket **_l = (struct bucket **)l; - struct bucket **_r = (struct bucket **)r; - - return GC_SECTORS_USED(*_l) >= GC_SECTORS_USED(*_r); -} - -static void new_bucket_swap(void *l, void *r, void __always_unused *args) -{ - struct bucket **_l = l; - struct bucket **_r = r; - - swap(*_l, *_r); + return GC_SECTORS_USED(l) < GC_SECTORS_USED(r); } static unsigned int bucket_heap_top(struct cache *ca) { struct bucket *b; - return (b = min_heap_peek(&ca->heap)[0]) ? GC_SECTORS_USED(b) : 0; + return (b = heap_peek(&ca->heap)) ? GC_SECTORS_USED(b) : 0; } void bch_moving_gc(struct cache_set *c) @@ -210,10 +199,6 @@ void bch_moving_gc(struct cache_set *c) struct cache *ca = c->cache; struct bucket *b; unsigned long sectors_to_move, reserve_sectors; - const struct min_heap_callbacks callbacks = { - .less = new_bucket_cmp, - .swp = new_bucket_swap, - }; if (!c->copy_gc_enabled) return; @@ -224,7 +209,7 @@ void bch_moving_gc(struct cache_set *c) reserve_sectors = ca->sb.bucket_size * fifo_used(&ca->free[RESERVE_MOVINGGC]); - ca->heap.nr = 0; + ca->heap.used = 0; for_each_bucket(b, ca) { if (GC_MARK(b) == GC_MARK_METADATA || @@ -233,31 +218,25 @@ void bch_moving_gc(struct cache_set *c) atomic_read(&b->pin)) continue; - if (!min_heap_full(&ca->heap)) { + if (!heap_full(&ca->heap)) { sectors_to_move += GC_SECTORS_USED(b); - min_heap_push(&ca->heap, &b, &callbacks, NULL); - } else if (!new_bucket_cmp(&b, min_heap_peek(&ca->heap), ca)) { + heap_add(&ca->heap, b, bucket_cmp); + } else if (bucket_cmp(b, heap_peek(&ca->heap))) { sectors_to_move -= bucket_heap_top(ca); sectors_to_move += GC_SECTORS_USED(b); ca->heap.data[0] = b; - min_heap_sift_down(&ca->heap, 0, &callbacks, NULL); + heap_sift(&ca->heap, 0, bucket_cmp); } } while (sectors_to_move > reserve_sectors) { - if (ca->heap.nr) { - b = min_heap_peek(&ca->heap)[0]; - min_heap_pop(&ca->heap, &callbacks, NULL); - } + heap_pop(&ca->heap, b, bucket_cmp); sectors_to_move -= GC_SECTORS_USED(b); } - while (ca->heap.nr) { - b = min_heap_peek(&ca->heap)[0]; - min_heap_pop(&ca->heap, &callbacks, NULL); + while (heap_pop(&ca->heap, b, bucket_cmp)) SET_GC_MOVE(b, 1); - } mutex_unlock(&c->bucket_lock); diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index 1efb768b2890..2ea490b9d370 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -1912,7 +1912,8 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb) INIT_LIST_HEAD(&c->btree_cache_freed); INIT_LIST_HEAD(&c->data_buckets); - iter_size = ((meta_bucket_pages(sb) * PAGE_SECTORS) / sb->block_size) * + iter_size = sizeof(struct btree_iter) + + ((meta_bucket_pages(sb) * PAGE_SECTORS) / sb->block_size) * sizeof(struct btree_iter_set); c->devices = kcalloc(c->nr_uuids, sizeof(void *), GFP_KERNEL); diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c index e8f696cb58c0..826b14cae4e5 100644 --- a/drivers/md/bcache/sysfs.c +++ b/drivers/md/bcache/sysfs.c @@ -660,9 +660,7 @@ static unsigned int bch_root_usage(struct cache_set *c) unsigned int bytes = 0; struct bkey *k; struct btree *b; - struct btree_iter iter; - - min_heap_init(&iter.heap, NULL, MAX_BSETS); + struct btree_iter_stack iter; goto lock_root; diff --git a/drivers/md/bcache/util.h b/drivers/md/bcache/util.h index 539454d8e2d0..f61ab1bada6c 100644 --- a/drivers/md/bcache/util.h +++ b/drivers/md/bcache/util.h @@ -9,7 +9,6 @@ #include <linux/kernel.h> #include <linux/sched/clock.h> #include <linux/llist.h> -#include <linux/min_heap.h> #include <linux/ratelimit.h> #include <linux/vmalloc.h> #include <linux/workqueue.h> @@ -31,10 +30,16 @@ struct closure; #endif +#define DECLARE_HEAP(type, name) \ + struct { \ + size_t size, used; \ + type *data; \ + } name + #define init_heap(heap, _size, gfp) \ ({ \ size_t _bytes; \ - (heap)->nr = 0; \ + (heap)->used = 0; \ (heap)->size = (_size); \ _bytes = (heap)->size * sizeof(*(heap)->data); \ (heap)->data = kvmalloc(_bytes, (gfp) & GFP_KERNEL); \ @@ -47,6 +52,64 @@ do { \ (heap)->data = NULL; \ } while (0) +#define heap_swap(h, i, j) swap((h)->data[i], (h)->data[j]) + +#define heap_sift(h, i, cmp) \ +do { \ + size_t _r, _j = i; \ + \ + for (; _j * 2 + 1 < (h)->used; _j = _r) { \ + _r = _j * 2 + 1; \ + if (_r + 1 < (h)->used && \ + cmp((h)->data[_r], (h)->data[_r + 1])) \ + _r++; \ + \ + if (cmp((h)->data[_r], (h)->data[_j])) \ + break; \ + heap_swap(h, _r, _j); \ + } \ +} while (0) + +#define heap_sift_down(h, i, cmp) \ +do { \ + while (i) { \ + size_t p = (i - 1) / 2; \ + if (cmp((h)->data[i], (h)->data[p])) \ + break; \ + heap_swap(h, i, p); \ + i = p; \ + } \ +} while (0) + +#define heap_add(h, d, cmp) \ +({ \ + bool _r = !heap_full(h); \ + if (_r) { \ + size_t _i = (h)->used++; \ + (h)->data[_i] = d; \ + \ + heap_sift_down(h, _i, cmp); \ + heap_sift(h, _i, cmp); \ + } \ + _r; \ +}) + +#define heap_pop(h, d, cmp) \ +({ \ + bool _r = (h)->used; \ + if (_r) { \ + (d) = (h)->data[0]; \ + (h)->used--; \ + heap_swap(h, 0, (h)->used); \ + heap_sift(h, 0, cmp); \ + } \ + _r; \ +}) + +#define heap_peek(h) ((h)->used ? (h)->data[0] : NULL) + +#define heap_full(h) ((h)->used == (h)->size) + #define DECLARE_FIFO(type, name) \ struct { \ size_t front, back, size, mask; \ diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c index 453efbbdc8ee..302e75f1fc4b 100644 --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -908,16 +908,15 @@ static int bch_dirty_init_thread(void *arg) struct dirty_init_thrd_info *info = arg; struct bch_dirty_init_state *state = info->state; struct cache_set *c = state->c; - struct btree_iter iter; + struct btree_iter_stack iter; struct bkey *k, *p; int cur_idx, prev_idx, skip_nr; k = p = NULL; prev_idx = 0; - min_heap_init(&iter.heap, NULL, MAX_BSETS); - bch_btree_iter_init(&c->root->keys, &iter, NULL); - k = bch_btree_iter_next_filter(&iter, &c->root->keys, bch_ptr_bad); + bch_btree_iter_stack_init(&c->root->keys, &iter, NULL); + k = bch_btree_iter_next_filter(&iter.iter, &c->root->keys, bch_ptr_bad); BUG_ON(!k); p = k; @@ -931,7 +930,7 @@ static int bch_dirty_init_thread(void *arg) skip_nr = cur_idx - prev_idx; while (skip_nr) { - k = bch_btree_iter_next_filter(&iter, + k = bch_btree_iter_next_filter(&iter.iter, &c->root->keys, bch_ptr_bad); if (k) @@ -980,13 +979,11 @@ void bch_sectors_dirty_init(struct bcache_device *d) int i; struct btree *b = NULL; struct bkey *k = NULL; - struct btree_iter iter; + struct btree_iter_stack iter; struct sectors_dirty_init op; struct cache_set *c = d->c; struct bch_dirty_init_state state; - min_heap_init(&iter.heap, NULL, MAX_BSETS); - retry_lock: b = c->root; rw_lock(0, b, b->level); -- 2.34.1

2 weeks, 2 days

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[PATCH v2 1/3] Revert "bcache: update min_heap_callbacks to use default builtin swap"

by Kuan-Wei Chiu

This reverts commit 3d8a9a1c35227c3f1b0bd132c9f0a80dbda07b65. Although removing the custom swap function simplified the code, this change is part of a broader migration to the generic min_heap API that introduced significant performance regressions in bcache. As reported by Robert, bcache now suffers from latency spikes, with P100 (max) latency increasing from 600 ms to 2.4 seconds every 5 minutes. These regressions degrade bcache's effectiveness as a low-latency cache layer and lead to frequent timeouts and application stalls in production environments. This revert is part of a series of changes to restore previous performance by undoing the min_heap transition. Link: https://lore.kernel.org/lkml/CAJhEC05+0S69z+3+FB2Cd0hD+pCRyWTKLEOsc8BOmH73p… Fixes: 866898efbb25 ("bcache: remove heap-related macros and switch to generic min_heap") Fixes: 92a8b224b833 ("lib/min_heap: introduce non-inline versions of min heap API functions") Reported-by: Robert Pang <robertpang(a)google.com> Closes: https://lore.kernel.org/linux-bcache/CAJhEC06F_AtrPgw2-7CvCqZgeStgCtitbD-ry… Cc: stable(a)vger.kernel.org Signed-off-by: Kuan-Wei Chiu <visitorckw(a)gmail.com> --- drivers/md/bcache/alloc.c | 11 +++++++++-- drivers/md/bcache/bset.c | 14 +++++++++++--- drivers/md/bcache/extents.c | 10 +++++++++- drivers/md/bcache/movinggc.c | 10 +++++++++- 4 files changed, 38 insertions(+), 7 deletions(-) diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c index 8998e61efa40..da50f6661bae 100644 --- a/drivers/md/bcache/alloc.c +++ b/drivers/md/bcache/alloc.c @@ -189,16 +189,23 @@ static inline bool new_bucket_min_cmp(const void *l, const void *r, void *args) return new_bucket_prio(ca, *lhs) < new_bucket_prio(ca, *rhs); } +static inline void new_bucket_swap(void *l, void *r, void __always_unused *args) +{ + struct bucket **lhs = l, **rhs = r; + + swap(*lhs, *rhs); +} + static void invalidate_buckets_lru(struct cache *ca) { struct bucket *b; const struct min_heap_callbacks bucket_max_cmp_callback = { .less = new_bucket_max_cmp, - .swp = NULL, + .swp = new_bucket_swap, }; const struct min_heap_callbacks bucket_min_cmp_callback = { .less = new_bucket_min_cmp, - .swp = NULL, + .swp = new_bucket_swap, }; ca->heap.nr = 0; diff --git a/drivers/md/bcache/bset.c b/drivers/md/bcache/bset.c index 68258a16e125..bd97d8626887 100644 --- a/drivers/md/bcache/bset.c +++ b/drivers/md/bcache/bset.c @@ -1093,6 +1093,14 @@ static inline bool new_btree_iter_cmp(const void *l, const void *r, void __alway return bkey_cmp(_l->k, _r->k) <= 0; } +static inline void new_btree_iter_swap(void *iter1, void *iter2, void __always_unused *args) +{ + struct btree_iter_set *_iter1 = iter1; + struct btree_iter_set *_iter2 = iter2; + + swap(*_iter1, *_iter2); +} + static inline bool btree_iter_end(struct btree_iter *iter) { return !iter->heap.nr; @@ -1103,7 +1111,7 @@ void bch_btree_iter_push(struct btree_iter *iter, struct bkey *k, { const struct min_heap_callbacks callbacks = { .less = new_btree_iter_cmp, - .swp = NULL, + .swp = new_btree_iter_swap, }; if (k != end) @@ -1149,7 +1157,7 @@ static inline struct bkey *__bch_btree_iter_next(struct btree_iter *iter, struct bkey *ret = NULL; const struct min_heap_callbacks callbacks = { .less = cmp, - .swp = NULL, + .swp = new_btree_iter_swap, }; if (!btree_iter_end(iter)) { @@ -1223,7 +1231,7 @@ static void btree_mergesort(struct btree_keys *b, struct bset *out, : bch_ptr_invalid; const struct min_heap_callbacks callbacks = { .less = b->ops->sort_cmp, - .swp = NULL, + .swp = new_btree_iter_swap, }; /* Heapify the iterator, using our comparison function */ diff --git a/drivers/md/bcache/extents.c b/drivers/md/bcache/extents.c index 4b84fda1530a..a7221e5dbe81 100644 --- a/drivers/md/bcache/extents.c +++ b/drivers/md/bcache/extents.c @@ -266,12 +266,20 @@ static bool new_bch_extent_sort_cmp(const void *l, const void *r, void __always_ return !(c ? c > 0 : _l->k < _r->k); } +static inline void new_btree_iter_swap(void *iter1, void *iter2, void __always_unused *args) +{ + struct btree_iter_set *_iter1 = iter1; + struct btree_iter_set *_iter2 = iter2; + + swap(*_iter1, *_iter2); +} + static struct bkey *bch_extent_sort_fixup(struct btree_iter *iter, struct bkey *tmp) { const struct min_heap_callbacks callbacks = { .less = new_bch_extent_sort_cmp, - .swp = NULL, + .swp = new_btree_iter_swap, }; while (iter->heap.nr > 1) { struct btree_iter_set *top = iter->heap.data, *i = top + 1; diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c index 45ca134cbf02..d6c73dd8eb2b 100644 --- a/drivers/md/bcache/movinggc.c +++ b/drivers/md/bcache/movinggc.c @@ -190,6 +190,14 @@ static bool new_bucket_cmp(const void *l, const void *r, void __always_unused *a return GC_SECTORS_USED(*_l) >= GC_SECTORS_USED(*_r); } +static void new_bucket_swap(void *l, void *r, void __always_unused *args) +{ + struct bucket **_l = l; + struct bucket **_r = r; + + swap(*_l, *_r); +} + static unsigned int bucket_heap_top(struct cache *ca) { struct bucket *b; @@ -204,7 +212,7 @@ void bch_moving_gc(struct cache_set *c) unsigned long sectors_to_move, reserve_sectors; const struct min_heap_callbacks callbacks = { .less = new_bucket_cmp, - .swp = NULL, + .swp = new_bucket_swap, }; if (!c->copy_gc_enabled) -- 2.34.1

2 weeks, 2 days

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[PATCH v2] fscrypt: don't use problematic non-inline crypto accelerators

by Eric Biggers

From: Eric Biggers <ebiggers(a)google.com> Make fscrypt no longer use Crypto API drivers for non-inline crypto accelerators, even when the Crypto API prioritizes them over CPU-based code (which unfortunately it often does). These drivers tend to be really problematic, especially for fscrypt's synchronous workload. Specifically, exclude drivers that have CRYPTO_ALG_KERN_DRIVER_ONLY or CRYPTO_ALG_ALLOCATES_MEMORY set. (Later, CRYPTO_ALG_ASYNC should be excluded too. That's omitted for now to keep this commit backportable, since until recently some CPU-based code had CRYPTO_ALG_ASYNC set.) There are two major issues with these drivers: bugs and performance. First, these drivers tend to be buggy. They're fundamentally much more error-prone and harder to test than the CPU-based code, and they often don't get tested before kernel releases. Released drivers have en/decrypted data incorrectly. These bugs cause real issues for fscrypt users who often didn't even want to use these drivers, for example: - https://github.com/google/fscryptctl/issues/32 - https://github.com/google/fscryptctl/issues/9 - https://lore.kernel.org/r/PH0PR02MB731916ECDB6C613665863B6CFFAA2@PH0PR02MB7… These drivers have also caused issues for dm-crypt users, including data corruption and deadlocks. Since Linux v5.10, dm-crypt has disabled most of these drivers by excluding CRYPTO_ALG_ALLOCATES_MEMORY. Second, the CPU-based crypto tends to be faster, often *much* faster. This may seem counterintuitive, but benchmarks clearly show it. There's a *lot* of overhead associated with going to a hardware driver, off the CPU, and back again. Measuring synchronous AES-256-XTS encryption of 4096-byte messages (fscrypt's workload) on two platforms with non-inline crypto accelerators that I have access to: Intel Emerald Rapids server: xts-aes-vaes-avx512: 16171 MB/s [CPU-based, Vector AES] xts(ecb(aes-generic)): 305 MB/s [CPU-based, generic C code] qat_aes_xts: 289 MB/s [Offload, Intel QuickAssist] Qualcomm SM8650 HDK: xts-aes-ce: 4301 MB/s [CPU-based, ARMv8 Crypto Extensions] xts(ecb(aes-generic)): 265 MB/s [CPU-based, generic C code] xts-aes-qce: 73 MB/s [Offload, Qualcomm Crypto Engine] So, using the "accelerators" is over 50 times slower than just using the CPU. Not only that, it's even slower than the generic C code, which suggests that even on platforms whose CPUs lack AES instructions the performance benefit of any accelerator would be marginal at best. The usefulness of the accelerators could be improved with a different software architecture that allows blocks to be efficiently en/decrypted in parallel. But fscrypt does not do that today, and even the async support in the Crypto API isn't really all that efficient. And even if the accelerator was used perfectly efficiently, it seems unlikely to help on small I/O requests, for which latency is really important. As of this writing, the Crypto API prioritizes qat_aes_xts over xts-aes-vaes-avx512. Therefore, this commit greatly improves fscrypt performance on Intel servers that have QAT and the QAT driver enabled. qat_aes_xts is going to be deprioritized in the Crypto API (like I did for xts-aes-qce recently too). But as this seems to be a common pattern with all the "accelerators", fscrypt should just disable all of them. An argument that has been given in favor of non-inline crypto accelerators is that they can protect keys in hardware. But fscrypt does not take advantage of that, so it is irrelevant. (Also, it would be quite difficult for fscrypt to do that.) Note that fscrypt does support inline encryption engines, using raw or hardware-wrapped keys. These actually do work well and are widely used. These do not use the "Crypto API" and are unaffected by this commit. Fixes: b30ab0e03407 ("ext4 crypto: add ext4 encryption facilities") Cc: stable(a)vger.kernel.org Signed-off-by: Eric Biggers <ebiggers(a)google.com> --- Changed in v2: - Improved commit message and comment - Dropped CRYPTO_ALG_ASYNC from the mask, to make this patch backport-friendly - Added Fixes and Cc stable fs/crypto/fscrypt_private.h | 16 ++++++++++++++++ fs/crypto/hkdf.c | 2 +- fs/crypto/keysetup.c | 3 ++- fs/crypto/keysetup_v1.c | 3 ++- 4 files changed, 21 insertions(+), 3 deletions(-) diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index c1d92074b65c5..0e95c7a095d49 100644 --- a/fs/crypto/fscrypt_private.h +++ b/fs/crypto/fscrypt_private.h @@ -43,10 +43,26 @@ * hardware-wrapped keys has made it misleading as it's only for raw keys. * Don't use it in kernel code; use one of the above constants instead. */ #undef FSCRYPT_MAX_KEY_SIZE +/* + * This mask is passed as the third argument to the crypto_alloc_*() functions + * to prevent fscrypt from using the Crypto API drivers for non-inline crypto + * accelerators. Those drivers have been problematic for fscrypt. fscrypt + * users have reported hangs and even incorrect en/decryption with these + * drivers. Since going to the driver, off CPU, and back again is really slow, + * such drivers can be over 50 times slower than the CPU-based code for + * fscrypt's synchronous workload. Even on platforms that lack AES instructions + * on the CPU, any performance benefit is likely to be marginal at best. + * + * Note that fscrypt also supports inline encryption engines. Those don't use + * the Crypto API and work much better than non-inline accelerators. + */ +#define FSCRYPT_CRYPTOAPI_MASK \ + (CRYPTO_ALG_ALLOCATES_MEMORY | CRYPTO_ALG_KERN_DRIVER_ONLY) + #define FSCRYPT_CONTEXT_V1 1 #define FSCRYPT_CONTEXT_V2 2 /* Keep this in sync with include/uapi/linux/fscrypt.h */ #define FSCRYPT_MODE_MAX FSCRYPT_MODE_AES_256_HCTR2 diff --git a/fs/crypto/hkdf.c b/fs/crypto/hkdf.c index 0f3028adc9c72..5b9c21cfe2b45 100644 --- a/fs/crypto/hkdf.c +++ b/fs/crypto/hkdf.c @@ -56,11 +56,11 @@ int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key, struct crypto_shash *hmac_tfm; static const u8 default_salt[HKDF_HASHLEN]; u8 prk[HKDF_HASHLEN]; int err; - hmac_tfm = crypto_alloc_shash(HKDF_HMAC_ALG, 0, 0); + hmac_tfm = crypto_alloc_shash(HKDF_HMAC_ALG, 0, FSCRYPT_CRYPTOAPI_MASK); if (IS_ERR(hmac_tfm)) { fscrypt_err(NULL, "Error allocating " HKDF_HMAC_ALG ": %ld", PTR_ERR(hmac_tfm)); return PTR_ERR(hmac_tfm); } diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c index 0d71843af9469..d8113a7196979 100644 --- a/fs/crypto/keysetup.c +++ b/fs/crypto/keysetup.c @@ -101,11 +101,12 @@ fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key, const struct inode *inode) { struct crypto_skcipher *tfm; int err; - tfm = crypto_alloc_skcipher(mode->cipher_str, 0, 0); + tfm = crypto_alloc_skcipher(mode->cipher_str, 0, + FSCRYPT_CRYPTOAPI_MASK); if (IS_ERR(tfm)) { if (PTR_ERR(tfm) == -ENOENT) { fscrypt_warn(inode, "Missing crypto API support for %s (API name: \"%s\")", mode->friendly_name, mode->cipher_str); diff --git a/fs/crypto/keysetup_v1.c b/fs/crypto/keysetup_v1.c index b70521c55132b..158ceae8a5bce 100644 --- a/fs/crypto/keysetup_v1.c +++ b/fs/crypto/keysetup_v1.c @@ -50,11 +50,12 @@ static int derive_key_aes(const u8 *master_key, { int res = 0; struct skcipher_request *req = NULL; DECLARE_CRYPTO_WAIT(wait); struct scatterlist src_sg, dst_sg; - struct crypto_skcipher *tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0); + struct crypto_skcipher *tfm = + crypto_alloc_skcipher("ecb(aes)", 0, FSCRYPT_CRYPTOAPI_MASK); if (IS_ERR(tfm)) { res = PTR_ERR(tfm); tfm = NULL; goto out; base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494 -- 2.49.0

2 weeks, 2 days

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Reply for - Mobile World Congress Shanghai 2025!

by Delilah Murray

Hi, Just wanted to check if you have received my previous email. Any update for me? Awaiting your reply. Regards, Delilah ___________________________________________________________________________________ From: Delilah Murray Subject: Attendee’s List “Mobile World Congress Shanghai 2025”. Hi, We're excited to offer exclusive access to the “Mobile World Congress Shanghai 2025” Visitor Contact List. Event Recap:- Date: 18 - 20 Jun 2025 Location: Shanghai, China Registrants Counts: 42,276 Visitors Contacts Data Fields Available: Individual Email Address, Cell Phone Number, Contact Name, Job Title, Company Name, Website, Physical Address, LinkedIn Profile, and more. This list gives you a direct line to your ideal audience—no gatekeepers, no guesswork. If you're interested in the list, just reply "Send me Pricing" or sample? Best regards, Delilah Murray Sr. Marketing Manager Prefer not to receive these emails? Just reply “NOT INTERESTED”.

2 weeks, 2 days

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Re: Patch "PCI: pciehp: Ignore Link Down/Up caused by Secondary Bus Reset" has been added to the 6.15-stable tree

by Lukas Wunner

[cc += Joel Mathew Thomas] On Tue, Jun 10, 2025 at 08:16:05AM -0400, Sasha Levin wrote: > This is a note to let you know that I've just added the patch titled > > PCI: pciehp: Ignore Link Down/Up caused by Secondary Bus Reset > > to the 6.15-stable tree which can be found at: > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… > > The filename of the patch is: > pci-pciehp-ignore-link-down-up-caused-by-secondary-b.patch > and it can be found in the queue-6.15 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let <stable(a)vger.kernel.org> know about it. Hi Sasha, thanks for selecting the above (which is 2af781a9edc4 upstream) as a 6.15 backport. A small feature request, could you amend the stable tooling to cc people tagged as Reported-by and Tested-by? I think they're the ones most interested in seeing something backported. Thanks! Lukas > commit 161a7237de69f65ccfe68da318343f3719149480 > Author: Lukas Wunner <lukas(a)wunner.de> > Date: Thu Apr 10 17:27:12 2025 +0200 > > PCI: pciehp: Ignore Link Down/Up caused by Secondary Bus Reset > > [ Upstream commit 2af781a9edc4ef5f6684c0710cc3542d9be48b31 ] > > When a Secondary Bus Reset is issued at a hotplug port, it causes a Data > Link Layer State Changed event as a side effect. On hotplug ports using > in-band presence detect, it additionally causes a Presence Detect Changed > event. > > These spurious events should not result in teardown and re-enumeration of > the device in the slot. Hence commit 2e35afaefe64 ("PCI: pciehp: Add > reset_slot() method") masked the Presence Detect Changed Enable bit in the > Slot Control register during a Secondary Bus Reset. Commit 06a8d89af551 > ("PCI: pciehp: Disable link notification across slot reset") additionally > masked the Data Link Layer State Changed Enable bit. > > However masking those bits only disables interrupt generation (PCIe r6.2 > sec 6.7.3.1). The events are still visible in the Slot Status register > and picked up by the IRQ handler if it runs during a Secondary Bus Reset. > This can happen if the interrupt is shared or if an unmasked hotplug event > occurs, e.g. Attention Button Pressed or Power Fault Detected. > > The likelihood of this happening used to be small, so it wasn't much of a > problem in practice. That has changed with the recent introduction of > bandwidth control in v6.13-rc1 with commit 665745f27487 ("PCI/bwctrl: > Re-add BW notification portdrv as PCIe BW controller"): > > Bandwidth control shares the interrupt with PCIe hotplug. A Secondary Bus > Reset causes a Link Bandwidth Notification, so the hotplug IRQ handler > runs, picks up the masked events and tears down the device in the slot. > > As a result, Joel reports VFIO passthrough failure of a GPU, which Ilpo > root-caused to the incorrect handling of masked hotplug events. > > Clearly, a more reliable way is needed to ignore spurious hotplug events. > > For Downstream Port Containment, a new ignore mechanism was introduced by > commit a97396c6eb13 ("PCI: pciehp: Ignore Link Down/Up caused by DPC"). > It has been working reliably for the past four years. > > Adapt it for Secondary Bus Resets. > > Introduce two helpers to annotate code sections which cause spurious link > changes: pci_hp_ignore_link_change() and pci_hp_unignore_link_change() > Use those helpers in lieu of masking interrupts in the Slot Control > register. > > Introduce a helper to check whether such a code section is executing > concurrently and if so, await it: pci_hp_spurious_link_change() > Invoke the helper in the hotplug IRQ thread pciehp_ist(). Re-use the > IRQ thread's existing code which ignores DPC-induced link changes unless > the link is unexpectedly down after reset recovery or the device was > replaced during the bus reset. > > That code block in pciehp_ist() was previously only executed if a Data > Link Layer State Changed event has occurred. Additionally execute it for > Presence Detect Changed events. That's necessary for compatibility with > PCIe r1.0 hotplug ports because Data Link Layer State Changed didn't exist > before PCIe r1.1. DPC was added with PCIe r3.1 and thus DPC-capable > hotplug ports always support Data Link Layer State Changed events. > But the same cannot be assumed for Secondary Bus Reset, which already > existed in PCIe r1.0. > > Secondary Bus Reset is only one of many causes of spurious link changes. > Others include runtime suspend to D3cold, firmware updates or FPGA > reconfiguration. The new pci_hp_{,un}ignore_link_change() helpers may be > used by all kinds of drivers to annotate such code sections, hence their > declarations are publicly visible in <linux/pci.h>. A case in point is > the Mellanox Ethernet driver which disables a firmware reset feature if > the Ethernet card is attached to a hotplug port, see commit 3d7a3f2612d7 > ("net/mlx5: Nack sync reset request when HotPlug is enabled"). Going > forward, PCIe hotplug will be able to cope gracefully with all such use > cases once the code sections are properly annotated. > > The new helpers internally use two bits in struct pci_dev's priv_flags as > well as a wait_queue. This mirrors what was done for DPC by commit > a97396c6eb13 ("PCI: pciehp: Ignore Link Down/Up caused by DPC"). That may > be insufficient if spurious link changes are caused by multiple sources > simultaneously. An example might be a Secondary Bus Reset issued by AER > during FPGA reconfiguration. If this turns out to happen in real life, > support for it can easily be added by replacing the PCI_LINK_CHANGING flag > with an atomic_t counter incremented by pci_hp_ignore_link_change() and > decremented by pci_hp_unignore_link_change(). Instead of awaiting a zero > PCI_LINK_CHANGING flag, the pci_hp_spurious_link_change() helper would > then simply await a zero counter. > > Fixes: 665745f27487 ("PCI/bwctrl: Re-add BW notification portdrv as PCIe BW controller") > Reported-by: Joel Mathew Thomas <proxy0(a)tutamail.com> > Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219765 > Signed-off-by: Lukas Wunner <lukas(a)wunner.de> > Signed-off-by: Bjorn Helgaas <bhelgaas(a)google.com> > Tested-by: Joel Mathew Thomas <proxy0(a)tutamail.com> > Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy(a)linux.intel.com> > Reviewed-by: Ilpo Järvinen <ilpo.jarvinen(a)linux.intel.com> > Link: https://patch.msgid.link/d04deaf49d634a2edf42bf3c06ed81b4ca54d17b.174429823… > Signed-off-by: Sasha Levin <sashal(a)kernel.org>

2 weeks, 2 days

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[PATCH 6.1 00/23] fixes from 6.11 for 6.1.y

by Leah Rumancik

Hello again, This is a series for 6.1.y for fixes from 6.11. It corresponds to the 6.6.y series here: https://lore.kernel.org/linux-xfs/20241218191725.63098-1-catherine.hoang@or… During porting, I noticed 6.1.y was missing a fix series from 6.5 that is a dependency of the fixes from 6.11 so I included those first. These were tested via the auto group on 9 configs with no regressions seen. These were also already ack'd on the xfs-stable mailing list. series from 6.5: https://lore.kernel.org/linux-xfs/168506055189.3727958.722711918040129046.s… 63ef7a35912d xfs: fix interval filtering in multi-step fsmap queries 7975aba19cba xfs: fix integer overflows in the fsmap rtbitmap and logdev backends d898137d789c xfs: fix getfsmap reporting past the last rt extent f045dd00328d xfs: clean up the rtbitmap fsmap backend a949a1c2a198 xfs: fix logdev fsmap query result filtering 3ee9351e7490 xfs: validate fsmap offsets specified in the query keys 75dc03453122 xfs: fix xfs_btree_query_range callers to initialize btree rec fully fix of 63ef7a35912dd ("xfs: fix interval filtering in multi-step fsmap queries") https://lore.kernel.org/linux-xfs/169335025661.3518128.12423331693506002020… cfa2df68b7ce xfs: fix an agbno overflow in __xfs_getfsmap_datadev 6.6 series for 6.11: https://lore.kernel.org/linux-xfs/20241218191725.63098-1-catherine.hoang@or… 85d0947db262 xfs: fix the contact address for the sysfs ABI documentation c08d03996cea xfs: verify buffer, inode, and dquot items every tx commit ff627196ddc1 xfs: use consistent uid/gid when grabbing dquots for inodes 7531c9ab2e55 xfs: declare xfs_file.c symbols in xfs_file.h c070b8802159 xfs: create a new helper to return a file's allocation unit 2e63ed9b0175 xfs: Fix xfs_flush_unmap_range() range for RT fe962ab3c4f1 xfs: Fix xfs_prepare_shift() range for RT ca96d83c9307 xfs: don't walk off the end of a directory data block 27336a327b40 xfs: remove unused parameter in macro XFS_DQUOT_LOGRES b2dcbd8a928c xfs: attr forks require attr, not attr2 4a82db7a4b73 xfs: conditionally allow FS_XFLAG_REALTIME changes if S_DAX is set 9fadc53d793c xfs: Fix the owner setting issue for rmap query in xfs fsmap 35bd108619c2 xfs: use XFS_BUF_DADDR_NULL for daddrs in getfsmap code 29fcb5fef608 xfs: take m_growlock when running growfsrt e5d1ae2d4d0b xfs: reset rootdir extent size hint after growfsrt [skipped for 6.1 as scrub is not supported in 6.1:] cb95cb2450e3 xfs: convert comma to semicolon 1bee32f33c0a xfs: fix file_path handling in tracepoints - Leah Christoph Hellwig (1): xfs: fix the contact address for the sysfs ABI documentation Darrick J. Wong (17): xfs: fix interval filtering in multi-step fsmap queries xfs: fix integer overflows in the fsmap rtbitmap and logdev backends xfs: fix getfsmap reporting past the last rt extent xfs: clean up the rtbitmap fsmap backend xfs: fix logdev fsmap query result filtering xfs: validate fsmap offsets specified in the query keys xfs: fix xfs_btree_query_range callers to initialize btree rec fully xfs: fix an agbno overflow in __xfs_getfsmap_datadev xfs: verify buffer, inode, and dquot items every tx commit xfs: use consistent uid/gid when grabbing dquots for inodes xfs: declare xfs_file.c symbols in xfs_file.h xfs: create a new helper to return a file's allocation unit xfs: attr forks require attr, not attr2 xfs: conditionally allow FS_XFLAG_REALTIME changes if S_DAX is set xfs: use XFS_BUF_DADDR_NULL for daddrs in getfsmap code xfs: take m_growlock when running growfsrt xfs: reset rootdir extent size hint after growfsrt John Garry (2): xfs: Fix xfs_flush_unmap_range() range for RT xfs: Fix xfs_prepare_shift() range for RT Julian Sun (1): xfs: remove unused parameter in macro XFS_DQUOT_LOGRES Zizhi Wo (1): xfs: Fix the owner setting issue for rmap query in xfs fsmap lei lu (1): xfs: don't walk off the end of a directory data block Documentation/ABI/testing/sysfs-fs-xfs | 8 +- fs/xfs/Kconfig | 12 ++ fs/xfs/libxfs/xfs_alloc.c | 10 +- fs/xfs/libxfs/xfs_dir2_data.c | 31 ++- fs/xfs/libxfs/xfs_dir2_priv.h | 7 + fs/xfs/libxfs/xfs_quota_defs.h | 2 +- fs/xfs/libxfs/xfs_refcount.c | 13 +- fs/xfs/libxfs/xfs_rmap.c | 10 +- fs/xfs/libxfs/xfs_trans_resv.c | 28 +-- fs/xfs/scrub/bmap.c | 8 +- fs/xfs/xfs.h | 4 + fs/xfs/xfs_bmap_util.c | 22 +- fs/xfs/xfs_buf_item.c | 32 +++ fs/xfs/xfs_dquot_item.c | 31 +++ fs/xfs/xfs_file.c | 33 ++- fs/xfs/xfs_file.h | 15 ++ fs/xfs/xfs_fsmap.c | 266 ++++++++++++++----------- fs/xfs/xfs_inode.c | 29 ++- fs/xfs/xfs_inode.h | 2 + fs/xfs/xfs_inode_item.c | 32 +++ fs/xfs/xfs_ioctl.c | 12 ++ fs/xfs/xfs_iops.c | 1 + fs/xfs/xfs_iops.h | 3 - fs/xfs/xfs_rtalloc.c | 78 ++++++-- fs/xfs/xfs_symlink.c | 8 +- fs/xfs/xfs_trace.h | 25 +++ 26 files changed, 505 insertions(+), 217 deletions(-) create mode 100644 fs/xfs/xfs_file.h -- 2.50.0.rc1.591.g9c95f17f64-goog

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Backport sh-sci fixes to 6.12.y

by Claudiu Beznea

Hi, stable team, Please backport the following commits to 6.12.y: 1/ 239f11209e5f ("serial: sh-sci: Move runtime PM enable to sci_probe_single()") 2/ 5f1017069933 ("serial: sh-sci: Clean sci_ports[0] after at earlycon exit") 3/ 651dee03696e ("serial: sh-sci: Increment the runtime usage counter for the earlycon device") These applies cleanly on top of 6.12.y (if applied in the order provided above) and fix the debug console on Renesas devices. Thank you, Claudiu Beznea

2 weeks, 2 days

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[PATCH AUTOSEL 6.15 001/118] net: macb: Check return value of dma_set_mask_and_coherent()

by Sasha Levin

From: Sergio Perez Gonzalez <sperezglz(a)gmail.com> [ Upstream commit 3920a758800762917177a6b5ab39707d8e376fe6 ] Issue flagged by coverity. Add a safety check for the return value of dma_set_mask_and_coherent, go to a safe exit if it returns error. Link: https://scan7.scan.coverity.com/#/project-view/53936/11354?selectedIssue=16… Signed-off-by: Sergio Perez Gonzalez <sperezglz(a)gmail.com> Reviewed-by: Claudiu Beznea <claudiu.beznea(a)tuxon.dev> Link: https://patch.msgid.link/20250526032034.84900-1-sperezglz@gmail.com Signed-off-by: Jakub Kicinski <kuba(a)kernel.org> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- Based on my analysis of the commit and the codebase context, here's my assessment: **YES** This commit should be backported to stable kernel trees. Here's my extensive analysis: ## Code Analysis The commit adds proper error checking for `dma_set_mask_and_coherent()` in the macb network driver. Looking at the specific changes: **Before the fix:** ```c if (GEM_BFEXT(DAW64, gem_readl(bp, DCFG6))) { dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(44)); bp->hw_dma_cap |= HW_DMA_CAP_64B; } ``` **After the fix:** ```c if (GEM_BFEXT(DAW64, gem_readl(bp, DCFG6))) { err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(44)); if (err) { dev_err(&pdev->dev, "failed to set DMA mask\n"); goto err_out_free_netdev; } bp->hw_dma_cap |= HW_DMA_CAP_64B; } ``` ## Why this should be backported: 1. **Fixes a Real Bug**: The original code ignores the return value of `dma_set_mask_and_coherent()`. If this function fails (which can happen on systems with restricted DMA capabilities), the driver would continue execution assuming 44-bit DMA addressing is available when it's not, leading to potential memory corruption or system crashes. 2. **Small, Contained Fix**: This is a minimal change that only adds proper error checking without changing any core logic or introducing new features. It follows the stable tree principle of being a small, targeted bugfix. 3. **Follows Established Patterns**: Looking at the similar commits provided, this matches exactly the pattern of commits marked "YES" for backporting (commits #1, #2, and #5) which all add proper error checking for DMA mask functions. 4. **Critical Network Driver**: The macb driver is used in production systems, and DMA-related bugs can cause data corruption or system instability, making this a high-priority fix for stable trees. 5. **Proper Error Handling Path**: The fix correctly uses the existing `err_out_free_netdev` label, which properly cleans up allocated resources (line 5373-5383 in macb_main.c), preventing resource leaks when DMA setup fails. 6. **Static Analysis Tool Flagged**: The commit message mentions this was flagged by Coverity, indicating it's a legitimate code quality issue that could manifest as a runtime bug. 7. **Matches Stable Tree Criteria**: - Important bugfix ✓ - Minimal risk of regression ✓ - No architectural changes ✓ - Confined to one driver/subsystem ✓ - Clear side effects (proper cleanup on failure) ✓ This commit addresses the same class of vulnerability as the other "YES" examples: ignoring return values of critical DMA functions that can fail and lead to undefined behavior. The fix is surgical, safe, and addresses a genuine runtime issue in a widely-used network driver. drivers/net/ethernet/cadence/macb_main.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c index e1e8bd2ec155b..d1f1ae5ea161c 100644 --- a/drivers/net/ethernet/cadence/macb_main.c +++ b/drivers/net/ethernet/cadence/macb_main.c @@ -5283,7 +5283,11 @@ static int macb_probe(struct platform_device *pdev) #ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT if (GEM_BFEXT(DAW64, gem_readl(bp, DCFG6))) { - dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(44)); + err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(44)); + if (err) { + dev_err(&pdev->dev, "failed to set DMA mask\n"); + goto err_out_free_netdev; + } bp->hw_dma_cap |= HW_DMA_CAP_64B; } #endif -- 2.39.5

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[PATCH 0/8] Fix bcache regression with equality-aware heap APIs

by Kuan-Wei Chiu

This patch series introduces equality-aware variants of the min heap API that use a top-down heapify strategy to improve performance when many elements are equal under the comparison function. It also updates the documentation accordingly and modifies bcache to use the new APIs to fix a performance regression caused by the switch to the generic min heap library. In particular, invalidate_buckets_lru() in bcache suffered from increased comparison overhead due to the bottom-up strategy introduced in commit 866898efbb25 ("bcache: remove heap-related macros and switch to generic min_heap"). The regression is addressed by switching to the equality-aware variants and using the inline versions to avoid function call overhead in this hot path. Cc: stable(a)vger.kernel.org --- To avoid duplicated effort and expedite resolution, Robert kindly agreed that I should submit my already-completed series instead. Many thanks to him for his cooperation and support. Kuan-Wei Chiu (8): lib min_heap: Add equal-elements-aware sift_down variant lib min_heap: Add typedef for sift_down function pointer lib min_heap: add eqaware variant of min_heapify_all() lib min_heap: add eqaware variant of min_heap_pop() lib min_heap: add eqaware variant of min_heap_pop_push() lib min_heap: add eqaware variant of min_heap_del() Documentation/core-api: min_heap: Document _eqaware variants of min-heap APIs bcache: Fix the tail IO latency regression by using equality-aware min heap API Documentation/core-api/min_heap.rst | 20 +++++ drivers/md/bcache/alloc.c | 15 ++-- include/linux/min_heap.h | 131 +++++++++++++++++++++++----- lib/min_heap.c | 23 +++-- 4 files changed, 154 insertions(+), 35 deletions(-) -- 2.34.1

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