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Old 06-20-2012, 07:24 PM
Mike Snitzer
 
Default dm transaction manager: handle space map checker failure

If CONFIG_DM_DEBUG_SPACE_MAPS is enabled and dm_sm_checker_create()
fails, dm_tm_create_internal() would still return success even though it
cleaned up all resources it was supposed to have created.

Fix the space map checker code to return an appropriate ERR_PTR and have
dm_tm_create_internal() check for it with IS_ERR.

Reported-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
---
drivers/md/persistent-data/dm-space-map-checker.c | 24 ++++++++++----------
.../md/persistent-data/dm-transaction-manager.c | 8 +++++-
2 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/drivers/md/persistent-data/dm-space-map-checker.c b/drivers/md/persistent-data/dm-space-map-checker.c
index 50ed53b..6d7c832 100644
--- a/drivers/md/persistent-data/dm-space-map-checker.c
+++ b/drivers/md/persistent-data/dm-space-map-checker.c
@@ -343,25 +343,25 @@ struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
int r;
struct sm_checker *smc;

- if (!sm)
- return NULL;
+ if (IS_ERR_OR_NULL(sm))
+ return ERR_PTR(-EINVAL);

smc = kmalloc(sizeof(*smc), GFP_KERNEL);
if (!smc)
- return NULL;
+ return ERR_PTR(-ENOMEM);

memcpy(&smc->sm, &ops_, sizeof(smc->sm));
r = ca_create(&smc->old_counts, sm);
if (r) {
kfree(smc);
- return NULL;
+ return ERR_PTR(r);
}

r = ca_create(&smc->counts, sm);
if (r) {
ca_destroy(&smc->old_counts);
kfree(smc);
- return NULL;
+ return ERR_PTR(r);
}

smc->real_sm = sm;
@@ -371,7 +371,7 @@ struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
ca_destroy(&smc->counts);
ca_destroy(&smc->old_counts);
kfree(smc);
- return NULL;
+ return ERR_PTR(r);
}

r = ca_commit(&smc->old_counts, &smc->counts);
@@ -379,7 +379,7 @@ struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
ca_destroy(&smc->counts);
ca_destroy(&smc->old_counts);
kfree(smc);
- return NULL;
+ return ERR_PTR(r);
}

return &smc->sm;
@@ -391,25 +391,25 @@ struct dm_space_map *dm_sm_checker_create_fresh(struct dm_space_map *sm)
int r;
struct sm_checker *smc;

- if (!sm)
- return NULL;
+ if (IS_ERR_OR_NULL(sm))
+ return ERR_PTR(-EINVAL);

smc = kmalloc(sizeof(*smc), GFP_KERNEL);
if (!smc)
- return NULL;
+ return ERR_PTR(-ENOMEM);

memcpy(&smc->sm, &ops_, sizeof(smc->sm));
r = ca_create(&smc->old_counts, sm);
if (r) {
kfree(smc);
- return NULL;
+ return ERR_PTR(r);
}

r = ca_create(&smc->counts, sm);
if (r) {
ca_destroy(&smc->old_counts);
kfree(smc);
- return NULL;
+ return ERR_PTR(r);
}

smc->real_sm = sm;
diff --git a/drivers/md/persistent-data/dm-transaction-manager.c b/drivers/md/persistent-data/dm-transaction-manager.c
index 02bf78e..e5604b3 100644
--- a/drivers/md/persistent-data/dm-transaction-manager.c
+++ b/drivers/md/persistent-data/dm-transaction-manager.c
@@ -347,8 +347,10 @@ static int dm_tm_create_internal(struct dm_block_manager *bm,
}

*sm = dm_sm_checker_create(inner);
- if (!*sm)
+ if (IS_ERR(*sm)) {
+ r = PTR_ERR(*sm);
goto bad2;
+ }

} else {
r = dm_bm_write_lock(dm_tm_get_bm(*tm), sb_location,
@@ -367,8 +369,10 @@ static int dm_tm_create_internal(struct dm_block_manager *bm,
}

*sm = dm_sm_checker_create(inner);
- if (!*sm)
+ if (IS_ERR(*sm)) {
+ r = PTR_ERR(*sm);
goto bad2;
+ }
}

return 0;
--
1.7.4.4

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Old 06-20-2012, 10:15 PM
Mike Snitzer
 
Default dm transaction manager: handle space map checker failure

On Wed, Jun 20 2012 at 5:37pm -0400,
Vivek Goyal <vgoyal@redhat.com> wrote:

> On Wed, Jun 20, 2012 at 05:20:10PM -0400, Vivek Goyal wrote:
> > On Wed, Jun 20, 2012 at 03:24:59PM -0400, Mike Snitzer wrote:
> > > If CONFIG_DM_DEBUG_SPACE_MAPS is enabled and dm_sm_checker_create()
> > > fails, dm_tm_create_internal() would still return success even though it
> > > cleaned up all resources it was supposed to have created.
> > >
> > > Fix the space map checker code to return an appropriate ERR_PTR and have
> > > dm_tm_create_internal() check for it with IS_ERR.
> > >
> >
> > I tested the patch and it works. It fails gracefully instead of segfaulting.
> >
> > device-mapper: reload ioctl failed: Cannot allocate memory
> >
> > I still do get waring though about large memory allocation. That's a
> > separate issue though.
>
> I put a trace_printk() in ca_create() to see how much memory we are trying
> to allocated using kzalloc. And answer is 10485760. Number of blocks
> obtained from space map is 2621440. I think this might be happening because
> my metadata device size is 10G.

It is. My metadata device is 1G and I'm seeing nr_blocks=262144

So kzalloc on your system cannot find 10M of contiguous memory.

How does this patch work for you?

diff --git a/drivers/md/persistent-data/dm-space-map-checker.c b/drivers/md/persistent-data/dm-space-map-checker.c
index 6d7c832..75ab11f 100644
--- a/drivers/md/persistent-data/dm-space-map-checker.c
+++ b/drivers/md/persistent-data/dm-space-map-checker.c
@@ -89,7 +89,7 @@ static int ca_create(struct count_array *ca, struct dm_space_map *sm)

ca->nr = nr_blocks;
ca->nr_free = nr_blocks;
- ca->counts = kzalloc(sizeof(*ca->counts) * nr_blocks, GFP_KERNEL);
+ ca->counts = vzalloc(sizeof(*ca->counts) * nr_blocks);
if (!ca->counts)
return -ENOMEM;


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Old 06-21-2012, 05:10 AM
Mike Snitzer
 
Default dm transaction manager: handle space map checker failure

On Wed, Jun 20 2012 at 6:15pm -0400,
Mike Snitzer <snitzer@redhat.com> wrote:

> On Wed, Jun 20 2012 at 5:37pm -0400,
> Vivek Goyal <vgoyal@redhat.com> wrote:
>
> > On Wed, Jun 20, 2012 at 05:20:10PM -0400, Vivek Goyal wrote:
> > > On Wed, Jun 20, 2012 at 03:24:59PM -0400, Mike Snitzer wrote:
> > > > If CONFIG_DM_DEBUG_SPACE_MAPS is enabled and dm_sm_checker_create()
> > > > fails, dm_tm_create_internal() would still return success even though it
> > > > cleaned up all resources it was supposed to have created.
> > > >
> > > > Fix the space map checker code to return an appropriate ERR_PTR and have
> > > > dm_tm_create_internal() check for it with IS_ERR.
> > > >
> > >
> > > I tested the patch and it works. It fails gracefully instead of segfaulting.
> > >
> > > device-mapper: reload ioctl failed: Cannot allocate memory
> > >
> > > I still do get waring though about large memory allocation. That's a
> > > separate issue though.
> >
> > I put a trace_printk() in ca_create() to see how much memory we are trying
> > to allocated using kzalloc. And answer is 10485760. Number of blocks
> > obtained from space map is 2621440. I think this might be happening because
> > my metadata device size is 10G.
>
> It is. My metadata device is 1G and I'm seeing nr_blocks=262144
>
> So kzalloc on your system cannot find 10M of contiguous memory.
>
> How does this patch work for you?

Hey Vivek,

Here is a more comprehensive patch (seems vmalloc doesn't support
passing a @size of 0, whereas kmalloc does).

But I know that this patch causes sm_checker_destroy() to crash in the
kfree() from ca_destroy(&smc->old_counts);

If I simply switch back from vzalloc to using kzalloc all works fine!?

Seems very odd, will dig deeper when I get a chance.

commit 65f1ea9401aeec7618626c3c32defbee5db30deb
Author: Mike Snitzer <snitzer@redhat.com>
Date: Thu Jun 21 00:05:18 2012 -0400

dm space map: fix error path of space map checker creation

diff --git a/drivers/md/persistent-data/dm-space-map-checker.c b/drivers/md/persistent-data/dm-space-map-checker.c
index 6d7c832..d4463dc 100644
--- a/drivers/md/persistent-data/dm-space-map-checker.c
+++ b/drivers/md/persistent-data/dm-space-map-checker.c
@@ -89,9 +89,13 @@ static int ca_create(struct count_array *ca, struct dm_space_map *sm)

ca->nr = nr_blocks;
ca->nr_free = nr_blocks;
- ca->counts = kzalloc(sizeof(*ca->counts) * nr_blocks, GFP_KERNEL);
- if (!ca->counts)
- return -ENOMEM;
+
+ if (nr_blocks) {
+ ca->counts = vzalloc(sizeof(*ca->counts) * nr_blocks);
+ if (!ca->counts)
+ return -ENOMEM;
+ } else
+ ca->counts = NULL;

return 0;
}
@@ -126,12 +130,14 @@ static int ca_load(struct count_array *ca, struct dm_space_map *sm)
static int ca_extend(struct count_array *ca, dm_block_t extra_blocks)
{
dm_block_t nr_blocks = ca->nr + extra_blocks;
- uint32_t *counts = kzalloc(sizeof(*counts) * nr_blocks, GFP_KERNEL);
+ uint32_t *counts = vzalloc(sizeof(*counts) * nr_blocks);
if (!counts)
return -ENOMEM;

- memcpy(counts, ca->counts, sizeof(*counts) * ca->nr);
- kfree(ca->counts);
+ if (ca->counts) {
+ memcpy(counts, ca->counts, sizeof(*counts) * ca->nr);
+ kfree(ca->counts);
+ }
ca->nr = nr_blocks;
ca->nr_free += extra_blocks;
ca->counts = counts;
diff --git a/drivers/md/persistent-data/dm-space-map-disk.c b/drivers/md/persistent-data/dm-space-map-disk.c
index 9535234..124828b 100644
--- a/drivers/md/persistent-data/dm-space-map-disk.c
+++ b/drivers/md/persistent-data/dm-space-map-disk.c
@@ -315,7 +315,13 @@ struct dm_space_map *dm_sm_disk_create(struct dm_transaction_manager *tm,
dm_block_t nr_blocks)
{
struct dm_space_map *sm = dm_sm_disk_create_real(tm, nr_blocks);
- return dm_sm_checker_create_fresh(sm);
+ struct dm_space_map *smc = dm_sm_checker_create_fresh(sm);
+
+ if (IS_ERR(smc) && !IS_ERR_OR_NULL(sm))
+ dm_sm_destroy(sm);
+ sm = smc;
+
+ return sm;
}
EXPORT_SYMBOL_GPL(dm_sm_disk_create);


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Old 06-21-2012, 06:10 AM
Mike Snitzer
 
Default dm transaction manager: handle space map checker failure

On Thu, Jun 21 2012 at 1:10am -0400,
Mike Snitzer <snitzer@redhat.com> wrote:

> Hey Vivek,
>
> Here is a more comprehensive patch (seems vmalloc doesn't support
> passing a @size of 0, whereas kmalloc does).
>
> But I know that this patch causes sm_checker_destroy() to crash in the
> kfree() from ca_destroy(&smc->old_counts);
>
> If I simply switch back from vzalloc to using kzalloc all works fine!?
>
> Seems very odd, will dig deeper when I get a chance.

Not odd, just a stupid oversight on my part. Needed to switch to using
vfree too

Here is an updated patch.

(Joe and Alasdair, I'll post 2 new cleaned up patches for 3.5; the
dm-space-map-disk.c change in this patch needs to be folded into v2 of
the "dm transaction manager: handle space map checker failure" patch I
posted yesterday)

drivers/md/persistent-data/dm-space-map-checker.c | 28 ++++++++++++--------
drivers/md/persistent-data/dm-space-map-disk.c | 8 +++++-
2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/drivers/md/persistent-data/dm-space-map-checker.c b/drivers/md/persistent-data/dm-space-map-checker.c
index 6d7c832..f0eded3 100644
--- a/drivers/md/persistent-data/dm-space-map-checker.c
+++ b/drivers/md/persistent-data/dm-space-map-checker.c
@@ -89,13 +89,22 @@ static int ca_create(struct count_array *ca, struct dm_space_map *sm)

ca->nr = nr_blocks;
ca->nr_free = nr_blocks;
- ca->counts = kzalloc(sizeof(*ca->counts) * nr_blocks, GFP_KERNEL);
- if (!ca->counts)
- return -ENOMEM;
+
+ if (nr_blocks) {
+ ca->counts = vzalloc(sizeof(*ca->counts) * nr_blocks);
+ if (!ca->counts)
+ return -ENOMEM;
+ } else
+ ca->counts = NULL;

return 0;
}

+static void ca_destroy(struct count_array *ca)
+{
+ vfree(ca->counts);
+}
+
static int ca_load(struct count_array *ca, struct dm_space_map *sm)
{
int r;
@@ -126,12 +135,14 @@ static int ca_load(struct count_array *ca, struct dm_space_map *sm)
static int ca_extend(struct count_array *ca, dm_block_t extra_blocks)
{
dm_block_t nr_blocks = ca->nr + extra_blocks;
- uint32_t *counts = kzalloc(sizeof(*counts) * nr_blocks, GFP_KERNEL);
+ uint32_t *counts = vzalloc(sizeof(*counts) * nr_blocks);
if (!counts)
return -ENOMEM;

- memcpy(counts, ca->counts, sizeof(*counts) * ca->nr);
- kfree(ca->counts);
+ if (ca->counts) {
+ memcpy(counts, ca->counts, sizeof(*counts) * ca->nr);
+ ca_destroy(ca);
+ }
ca->nr = nr_blocks;
ca->nr_free += extra_blocks;
ca->counts = counts;
@@ -151,11 +162,6 @@ static int ca_commit(struct count_array *old, struct count_array *new)
return 0;
}

-static void ca_destroy(struct count_array *ca)
-{
- kfree(ca->counts);
-}
-
/*----------------------------------------------------------------*/

struct sm_checker {
diff --git a/drivers/md/persistent-data/dm-space-map-disk.c b/drivers/md/persistent-data/dm-space-map-disk.c
index 9535234..124828b 100644
--- a/drivers/md/persistent-data/dm-space-map-disk.c
+++ b/drivers/md/persistent-data/dm-space-map-disk.c
@@ -315,7 +315,13 @@ struct dm_space_map *dm_sm_disk_create(struct dm_transaction_manager *tm,
dm_block_t nr_blocks)
{
struct dm_space_map *sm = dm_sm_disk_create_real(tm, nr_blocks);
- return dm_sm_checker_create_fresh(sm);
+ struct dm_space_map *smc = dm_sm_checker_create_fresh(sm);
+
+ if (IS_ERR(smc) && !IS_ERR_OR_NULL(sm))
+ dm_sm_destroy(sm);
+ sm = smc;
+
+ return sm;
}
EXPORT_SYMBOL_GPL(dm_sm_disk_create);


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Old 06-25-2012, 12:16 PM
Joe Thornber
 
Default dm transaction manager: handle space map checker failure

On Thu, Jun 21, 2012 at 02:10:09AM -0400, Mike Snitzer wrote:
> (Joe and Alasdair, I'll post 2 new cleaned up patches for 3.5; the
> dm-space-map-disk.c change in this patch needs to be folded into v2 of
> the "dm transaction manager: handle space map checker failure" patch I
> posted yesterday)

I think it's time to pull that checker completely. Confidence in the
space maps is higher these days, and this checker is very expensive in
memory for realistic sized pools.

- Joe

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