linux-bcache.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Coly Li <colyli@suse.de>
To: linux-bcache@vger.kernel.org
Cc: linux-block@vger.kernel.org, Coly Li <colyli@suse.de>
Subject: [PATCH v2 13/17] bcache: handle btree node memory allocation properly for bucket size > 8MB
Date: Wed, 15 Jul 2020 13:46:08 +0800	[thread overview]
Message-ID: <20200715054612.6349-14-colyli@suse.de> (raw)
In-Reply-To: <20200715054612.6349-1-colyli@suse.de>

Currently the bcache internal btree node occupies a whole bucket. When
loading the btree node from cache device into memory, mca_data_alloc()
will call bch_btree_keys_alloc() to allocate memory for the whole bucket
size, ilog2(b->c->btree_pages) is send to bch_btree_keys_alloc() as the
parameter 'page_order'.

c->btree_pages is set as bucket_pages() in bch_cache_set_alloc(), for
bucket size > 8MB, ilog2(b->c->btree_pages) is 12 for 4KB page size. By
default the maximum page order __get_free_pages() accepts is MAX_ORDER
(11), in this condition bch_btree_keys_alloc() will always fail.

Because of other over-page-order allocation failure fails the cache
device registration, such btree node allocation failure wasn't observed
during runtime. After other blocking page allocation failures for bucket
size > 8MB, this btree node allocation issue may trigger potentical risk
e.g. infinite dead-loop to retry btree node allocation after failure.

This patch fixes the potential problem by setting c->btree_pages to
meta_bucket_pages() in bch_cache_set_alloc(). In the condition that
bucket size > 8MB, meta_bucket_pages() will always return a number which
won't exceed the maximum page order of the buddy allocator.

Signed-off-by: Coly Li <colyli@suse.de>
---
 drivers/md/bcache/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index e2c28aa5531c..334596b8d264 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1867,7 +1867,7 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
 	c->nr_uuids		= meta_bucket_bytes(&c->sb) / sizeof(struct uuid_entry);
 	c->devices_max_used	= 0;
 	atomic_set(&c->attached_dev_nr, 0);
-	c->btree_pages		= bucket_pages(c);
+	c->btree_pages		= meta_bucket_pages(&c->sb);
 	if (c->btree_pages > BTREE_MAX_PAGES)
 		c->btree_pages = max_t(int, c->btree_pages / 4,
 				       BTREE_MAX_PAGES);
-- 
2.26.2


  parent reply	other threads:[~2020-07-15  5:46 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-15  5:45 [PATCH v2 00/17] bcache: extend bucket size to 32bit width Coly Li
2020-07-15  5:45 ` [PATCH v2 01/17] bcache: add comments to mark member offset of struct cache_sb_disk Coly Li
2020-07-15  6:02   ` Hannes Reinecke
2020-07-15  9:03     ` Coly Li
2020-07-15  9:08       ` Johannes Thumshirn
2020-07-15 10:35         ` Coly Li
2020-07-15  5:45 ` [PATCH v2 02/17] bcache: add read_super_basic() to read major part of super block Coly Li
2020-07-15  6:03   ` Hannes Reinecke
2020-07-15  5:45 ` [PATCH v2 03/17] bcache: add more accurate error information in read_super_basic() Coly Li
2020-07-15  6:04   ` Hannes Reinecke
2020-07-15  5:45 ` [PATCH v2 04/17] bcache: disassemble the big if() checks in bch_cache_set_alloc() Coly Li
2020-07-15  6:08   ` Hannes Reinecke
2020-07-15  5:46 ` [PATCH v2 05/17] bcache: fix super block seq numbers comparision in register_cache_set() Coly Li
2020-07-15  6:10   ` Hannes Reinecke
2020-07-15  5:46 ` [PATCH v2 06/17] bcache: increase super block version for cache device and backing device Coly Li
2020-07-15  6:11   ` Hannes Reinecke
2020-07-15  5:46 ` [PATCH v2 07/17] bcache: move bucket related code into read_super_basic() Coly Li
2020-07-15  6:44   ` Hannes Reinecke
2020-07-15  5:46 ` [PATCH v2 08/17] bcache: struct cache_sb is only for in-memory super block now Coly Li
2020-07-15  6:45   ` Hannes Reinecke
2020-07-15  5:46 ` [PATCH v2 09/17] bcache: introduce meta_bucket_pages() related helper routines Coly Li
2020-07-15  5:46 ` [PATCH v2 10/17] bcache: handle c->uuids properly for bucket size > 8MB Coly Li
2020-07-15  5:46 ` [PATCH v2 11/17] bcache: handle cache prio_buckets and disk_buckets " Coly Li
2020-07-15  5:46 ` [PATCH v2 12/17] bcache: handle cache set verify_ondisk " Coly Li
2020-07-15  5:46 ` Coly Li [this message]
2020-07-15  5:46 ` [PATCH v2 14/17] bcache: add bucket_size_hi into struct cache_sb_disk for large bucket Coly Li
2020-07-15  5:46 ` [PATCH v2 15/17] bcache: add sysfs file to display feature sets information of cache set Coly Li
2020-07-15  5:46 ` [PATCH v2 16/17] bcache: avoid extra memory allocation from mempool c->fill_iter Coly Li
2020-07-15  5:46 ` [PATCH v2 17/17] bcache: avoid extra memory consumption in struct bbio for large bucket size Coly Li

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200715054612.6349-14-colyli@suse.de \
    --to=colyli@suse.de \
    --cc=linux-bcache@vger.kernel.org \
    --cc=linux-block@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).