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From: Coly Li <colyli@suse.de>
To: linux-bcache@vger.kernel.org
Cc: linux-block@vger.kernel.org, Coly Li <colyli@suse.de>
Subject: [RFC PATCH 12/16] bcache: handle cache set verify_ondisk properly for bucket size > 8MB
Date: Sun,  5 Jul 2020 23:55:57 +0800
Message-ID: <20200705155601.5404-13-colyli@suse.de> (raw)
Message-ID: <20200705155557.0WkJ4XW1VN_bpmpjTwAQ1FhXHq8L6DdLNCXlbRfaawk@z> (raw)
In-Reply-To: <20200705155601.5404-1-colyli@suse.de>

In bch_btree_cache_alloc() when CONFIG_BCACHE_DEBUG is configured,
allocate memory for c->verify_ondisk may fail if the bucket size > 8MB,
which will require __get_free_pages() to allocate continuous pages
with order > 11 (the default MAX_ORDER of Linux buddy allocator). Such
over size allocation will fail, and cause 2 problems,
- When CONFIG_BCACHE_DEBUG is configured,  bch_btree_verify() does not
  work, because c->verify_ondisk is NULL and bch_btree_verify() returns
  immediately.
- bch_btree_cache_alloc() will fail due to c->verify_ondisk allocation
  failed, then the whole cache device registration fails. And because of
  this failure, the first problem of bch_btree_verify() has no chance to
  be triggered.

This patch fixes the above problem by two means,
1) If pages allocation of c->verify_ondisk fails, set it to NULL and
   returns bch_btree_cache_alloc() with -ENOMEM.
2) When calling __get_free_pages() to allocate c->verify_ondisk pages,
   use ilog2(meta_bucket_pages(&c->sb)) to make sure ilog2() will always
   generate a pages order <= MAX_ORDER (or CONFIG_FORCE_MAX_ZONEORDER).
   Then the buddy system won't directly reject the allocation request.

Signed-off-by: Coly Li <colyli@suse.de>
---
 drivers/md/bcache/btree.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 6548a601edf0..a9d59b6c7d85 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -738,7 +738,7 @@ void bch_btree_cache_free(struct cache_set *c)
 	if (c->verify_data)
 		list_move(&c->verify_data->list, &c->btree_cache);
 
-	free_pages((unsigned long) c->verify_ondisk, ilog2(bucket_pages(c)));
+	free_pages((unsigned long) c->verify_ondisk, ilog2(meta_bucket_pages(&c->sb)));
 #endif
 
 	list_splice(&c->btree_cache_freeable,
@@ -785,7 +785,15 @@ int bch_btree_cache_alloc(struct cache_set *c)
 	mutex_init(&c->verify_lock);
 
 	c->verify_ondisk = (void *)
-		__get_free_pages(GFP_KERNEL, ilog2(bucket_pages(c)));
+		__get_free_pages(GFP_KERNEL, ilog2(meta_bucket_pages(&c->sb)));
+	if (!c->verify_ondisk) {
+		/*
+		 * Don't worry about the mca_rereserve buckets
+		 * allocated in previous for-loop, they will be
+		 * handled properly in bch_cache_set_unregister().
+		 */
+		return -ENOMEM;
+	}
 
 	c->verify_data = mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL);
 
-- 
2.26.2


  parent reply index

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-05 15:55 [RFC PATCH 00/16] bcache: extend bucket size to 32bit width Coly Li
2020-07-05 15:55 ` [RFC PATCH 01/16] bcache: add comments to mark member offset of struct cache_sb_disk Coly Li
2020-07-05 15:55 ` [RFC PATCH 02/16] bcache: add read_super_basic() to read major part of super block Coly Li
2020-07-05 15:55   ` Coly Li
2020-07-05 15:55 ` [RFC PATCH 03/16] bcache: add more accurate error information in read_super_basic() Coly Li
2020-07-05 15:55   ` Coly Li
2020-07-05 15:55 ` [RFC PATCH 04/16] bcache: disassemble the big if() checks in bch_cache_set_alloc() Coly Li
2020-07-05 15:55   ` Coly Li
2020-07-05 15:55 ` [RFC PATCH 05/16] bcache: fix super block seq numbers comparision in register_cache_set() Coly Li
2020-07-05 15:55 ` [RFC PATCH 06/16] bcache: increase super block version for cache device and backing device Coly Li
2020-07-05 15:55 ` [RFC PATCH 07/16] bcache: move bucket related code into read_super_basic() Coly Li
2020-07-05 15:55 ` [RFC PATCH 08/16] bcache: struct cache_sb is only for in-memory super block now Coly Li
2020-07-05 15:55 ` [RFC PATCH 09/16] bcache: introduce meta_bucket_pages() related helper routines Coly Li
2020-07-05 15:55   ` Coly Li
2020-07-05 15:55 ` [RFC PATCH 10/16] bcache: handle c->uuids properly for bucket size > 8MB Coly Li
2020-07-05 15:55 ` [RFC PATCH 11/16] bcache: handle cache prio_buckets and disk_buckets " Coly Li
2020-07-05 15:55 ` Coly Li [this message]
2020-07-05 15:55   ` [RFC PATCH 12/16] bcache: handle cache set verify_ondisk " Coly Li
2020-07-05 15:55 ` [RFC PATCH 13/16] bcache: handle btree node memory allocation " Coly Li
2020-07-05 15:55   ` Coly Li
2020-07-05 15:55 ` [RFC PATCH 14/16] bcache: add bucket_size_hi into struct cache_sb_disk for large bucket Coly Li
2020-07-05 15:56 ` [RFC PATCH 15/16] bcache: avoid extra memory allocation from mempool c->fill_iter Coly Li
2020-07-05 15:56 ` [RFC PATCH 16/16] bcache: avoid extra memory consumption in struct bbio for large bucket size Coly Li

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