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authorMikulas Patocka <mpatocka@redhat.com>2015-11-23 19:20:06 -0500
committerMike Snitzer <snitzer@redhat.com>2015-12-10 10:38:58 -0500
commit86bad0c7071c24efee0a395d8b622764bdd24320 (patch)
tree49fa95844e79ed05c16735dfa31cb6953683836d /drivers/md/Kconfig
parentf98c8f797021e78ba27143ecd39c51995c47aa8b (diff)
downloadlinux-86bad0c7071c24efee0a395d8b622764bdd24320.tar.bz2
dm bufio: store stacktrace in buffers to help find buffer leaks
The option DM_DEBUG_BLOCK_STACK_TRACING is moved from persistent-data directory to device mapper directory because it will now be used by persistent-data and bufio. When the option is enabled, each bufio buffer stores the stacktrace of the last dm_bufio_get(), dm_bufio_read() or dm_bufio_new() call that increased the hold count to 1. The buffer's stacktrace is printed if the buffer was not released before the bufio client is destroyed. When DM_DEBUG_BLOCK_STACK_TRACING is enabled, any bufio buffer leaks are considered warnings - i.e. the kernel continues afterwards. If not enabled, buffer leaks are considered BUGs and the kernel with crash. Reasoning on this disposition is: if we only ever warned on buffer leaks users would generally ignore them and the problematic code would never get fixed. Successfully used to find source of bufio leaks fixed with commit fce079f63c3 ("dm btree: fix bufio buffer leaks in dm_btree_del() error path"). Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/Kconfig')
-rw-r--r--drivers/md/Kconfig9
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 7913fdcfc849..1b69359461e9 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -240,6 +240,15 @@ config DM_BUFIO
as a cache, holding recently-read blocks in memory and performing
delayed writes.
+config DM_DEBUG_BLOCK_STACK_TRACING
+ bool "Keep stack trace of persistent data block lock holders"
+ depends on STACKTRACE_SUPPORT && DM_BUFIO
+ select STACKTRACE
+ ---help---
+ Enable this for messages that may help debug problems with the
+ block manager locking used by thin provisioning and caching.
+
+ If unsure, say N.
config DM_BIO_PRISON
tristate
depends on BLK_DEV_DM