* [PATCH] xen-blkfront: fix kernel panic with negotiate_mq error path
@ 2018-10-29 18:31 Manjunath Patil
2018-10-30 7:04 ` Juergen Gross
2018-10-30 10:39 ` Roger Pau Monné
0 siblings, 2 replies; 5+ messages in thread
From: Manjunath Patil @ 2018-10-29 18:31 UTC (permalink / raw)
To: boris.ostrovsky, jgross, konrad.wilk, roger.pau
Cc: axboe, xen-devel, linux-block, linux-kernel
info->nr_rings isn't adjusted in case of ENOMEM error from
negotiate_mq(). This leads to kernel panic in error path.
Typical call stack involving panic -
#8 page_fault at ffffffff8175936f
[exception RIP: blkif_free_ring+33]
RIP: ffffffffa0149491 RSP: ffff8804f7673c08 RFLAGS: 00010292
...
#9 blkif_free at ffffffffa0149aaa [xen_blkfront]
#10 talk_to_blkback at ffffffffa014c8cd [xen_blkfront]
#11 blkback_changed at ffffffffa014ea8b [xen_blkfront]
#12 xenbus_otherend_changed at ffffffff81424670
#13 backend_changed at ffffffff81426dc3
#14 xenwatch_thread at ffffffff81422f29
#15 kthread at ffffffff810abe6a
#16 ret_from_fork at ffffffff81754078
Though either of my changes avoid the panic, I included both the
changes. This issue got introduced with "7ed8ce1 xen-blkfront: move
negotiate_mq to cover all cases of new VBDs"
Signed-off-by: Manjunath Patil <manjunath.b.patil@oracle.com>
---
drivers/block/xen-blkfront.c | 7 +++++--
1 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 429d201..dc8fe25 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1350,8 +1350,10 @@ static void blkif_free(struct blkfront_info *info, int suspend)
if (info->rq)
blk_mq_stop_hw_queues(info->rq);
- for (i = 0; i < info->nr_rings; i++)
- blkif_free_ring(&info->rinfo[i]);
+ if (info->rinfo) {
+ for (i = 0; i < info->nr_rings; i++)
+ blkif_free_ring(&info->rinfo[i]);
+ }
kfree(info->rinfo);
info->rinfo = NULL;
@@ -1919,6 +1921,7 @@ static int negotiate_mq(struct blkfront_info *info)
GFP_KERNEL);
if (!info->rinfo) {
xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
+ info->nr_rings = 0;
return -ENOMEM;
}
--
1.7.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] xen-blkfront: fix kernel panic with negotiate_mq error path
2018-10-29 18:31 [PATCH] xen-blkfront: fix kernel panic with negotiate_mq error path Manjunath Patil
@ 2018-10-30 7:04 ` Juergen Gross
2018-10-30 16:27 ` [Xen-devel] " Manjunath Patil
2018-10-30 10:39 ` Roger Pau Monné
1 sibling, 1 reply; 5+ messages in thread
From: Juergen Gross @ 2018-10-30 7:04 UTC (permalink / raw)
To: Manjunath Patil, boris.ostrovsky, konrad.wilk, roger.pau
Cc: axboe, xen-devel, linux-block, linux-kernel
On 29/10/2018 19:31, Manjunath Patil wrote:
> info->nr_rings isn't adjusted in case of ENOMEM error from
> negotiate_mq(). This leads to kernel panic in error path.
>
> Typical call stack involving panic -
> #8 page_fault at ffffffff8175936f
> [exception RIP: blkif_free_ring+33]
> RIP: ffffffffa0149491 RSP: ffff8804f7673c08 RFLAGS: 00010292
> ...
> #9 blkif_free at ffffffffa0149aaa [xen_blkfront]
> #10 talk_to_blkback at ffffffffa014c8cd [xen_blkfront]
> #11 blkback_changed at ffffffffa014ea8b [xen_blkfront]
> #12 xenbus_otherend_changed at ffffffff81424670
> #13 backend_changed at ffffffff81426dc3
> #14 xenwatch_thread at ffffffff81422f29
> #15 kthread at ffffffff810abe6a
> #16 ret_from_fork at ffffffff81754078
>
> Though either of my changes avoid the panic, I included both the
> changes. This issue got introduced with "7ed8ce1 xen-blkfront: move
> negotiate_mq to cover all cases of new VBDs"
Please us the correct format for specifying another commit.
> Signed-off-by: Manjunath Patil <manjunath.b.patil@oracle.com>
Can you please add a "Fixes:" tag and "Cc: stable@vger.kernel.org" ?
> ---
> drivers/block/xen-blkfront.c | 7 +++++--
> 1 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> index 429d201..dc8fe25 100644
> --- a/drivers/block/xen-blkfront.c
> +++ b/drivers/block/xen-blkfront.c
> @@ -1350,8 +1350,10 @@ static void blkif_free(struct blkfront_info *info, int suspend)
> if (info->rq)
> blk_mq_stop_hw_queues(info->rq);
>
> - for (i = 0; i < info->nr_rings; i++)
> - blkif_free_ring(&info->rinfo[i]);
> + if (info->rinfo) {
> + for (i = 0; i < info->nr_rings; i++)
> + blkif_free_ring(&info->rinfo[i]);
> + }
I'd drop this change.
>
> kfree(info->rinfo);
> info->rinfo = NULL;
> @@ -1919,6 +1921,7 @@ static int negotiate_mq(struct blkfront_info *info)
> GFP_KERNEL);
> if (!info->rinfo) {
> xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
> + info->nr_rings = 0;
> return -ENOMEM;
> }
Juergen
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [Xen-devel] [PATCH] xen-blkfront: fix kernel panic with negotiate_mq error path
2018-10-30 7:04 ` Juergen Gross
@ 2018-10-30 16:27 ` Manjunath Patil
0 siblings, 0 replies; 5+ messages in thread
From: Manjunath Patil @ 2018-10-30 16:27 UTC (permalink / raw)
To: Juergen Gross, boris.ostrovsky, konrad.wilk, roger.pau
Cc: axboe, xen-devel, linux-block, linux-kernel
Thank you Juergen for your comments.
I will soon send v2 patch.
-Thanks,
Manjunath
On 10/30/2018 12:04 AM, Juergen Gross wrote:
> On 29/10/2018 19:31, Manjunath Patil wrote:
>> info->nr_rings isn't adjusted in case of ENOMEM error from
>> negotiate_mq(). This leads to kernel panic in error path.
>>
>> Typical call stack involving panic -
>> #8 page_fault at ffffffff8175936f
>> [exception RIP: blkif_free_ring+33]
>> RIP: ffffffffa0149491 RSP: ffff8804f7673c08 RFLAGS: 00010292
>> ...
>> #9 blkif_free at ffffffffa0149aaa [xen_blkfront]
>> #10 talk_to_blkback at ffffffffa014c8cd [xen_blkfront]
>> #11 blkback_changed at ffffffffa014ea8b [xen_blkfront]
>> #12 xenbus_otherend_changed at ffffffff81424670
>> #13 backend_changed at ffffffff81426dc3
>> #14 xenwatch_thread at ffffffff81422f29
>> #15 kthread at ffffffff810abe6a
>> #16 ret_from_fork at ffffffff81754078
>>
>> Though either of my changes avoid the panic, I included both the
>> changes. This issue got introduced with "7ed8ce1 xen-blkfront: move
>> negotiate_mq to cover all cases of new VBDs"
> Please us the correct format for specifying another commit.
>
>> Signed-off-by: Manjunath Patil <manjunath.b.patil@oracle.com>
> Can you please add a "Fixes:" tag and "Cc: stable@vger.kernel.org" ?
>
>> ---
>> drivers/block/xen-blkfront.c | 7 +++++--
>> 1 files changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
>> index 429d201..dc8fe25 100644
>> --- a/drivers/block/xen-blkfront.c
>> +++ b/drivers/block/xen-blkfront.c
>> @@ -1350,8 +1350,10 @@ static void blkif_free(struct blkfront_info *info, int suspend)
>> if (info->rq)
>> blk_mq_stop_hw_queues(info->rq);
>>
>> - for (i = 0; i < info->nr_rings; i++)
>> - blkif_free_ring(&info->rinfo[i]);
>> + if (info->rinfo) {
>> + for (i = 0; i < info->nr_rings; i++)
>> + blkif_free_ring(&info->rinfo[i]);
>> + }
> I'd drop this change.
>
>>
>> kfree(info->rinfo);
>> info->rinfo = NULL;
>> @@ -1919,6 +1921,7 @@ static int negotiate_mq(struct blkfront_info *info)
>> GFP_KERNEL);
>> if (!info->rinfo) {
>> xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
>> + info->nr_rings = 0;
>> return -ENOMEM;
>> }
>
> Juergen
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] xen-blkfront: fix kernel panic with negotiate_mq error path
2018-10-29 18:31 [PATCH] xen-blkfront: fix kernel panic with negotiate_mq error path Manjunath Patil
2018-10-30 7:04 ` Juergen Gross
@ 2018-10-30 10:39 ` Roger Pau Monné
2018-10-30 16:29 ` [Xen-devel] " Manjunath Patil
1 sibling, 1 reply; 5+ messages in thread
From: Roger Pau Monné @ 2018-10-30 10:39 UTC (permalink / raw)
To: Manjunath Patil
Cc: boris.ostrovsky, jgross, konrad.wilk, axboe, xen-devel,
linux-block, linux-kernel
On Mon, Oct 29, 2018 at 11:31:56AM -0700, Manjunath Patil wrote:
> info->nr_rings isn't adjusted in case of ENOMEM error from
> negotiate_mq(). This leads to kernel panic in error path.
>
> Typical call stack involving panic -
> #8 page_fault at ffffffff8175936f
> [exception RIP: blkif_free_ring+33]
> RIP: ffffffffa0149491 RSP: ffff8804f7673c08 RFLAGS: 00010292
> ...
> #9 blkif_free at ffffffffa0149aaa [xen_blkfront]
> #10 talk_to_blkback at ffffffffa014c8cd [xen_blkfront]
> #11 blkback_changed at ffffffffa014ea8b [xen_blkfront]
> #12 xenbus_otherend_changed at ffffffff81424670
> #13 backend_changed at ffffffff81426dc3
> #14 xenwatch_thread at ffffffff81422f29
> #15 kthread at ffffffff810abe6a
> #16 ret_from_fork at ffffffff81754078
>
> Though either of my changes avoid the panic, I included both the
> changes. This issue got introduced with "7ed8ce1 xen-blkfront: move
> negotiate_mq to cover all cases of new VBDs"
>
> Signed-off-by: Manjunath Patil <manjunath.b.patil@oracle.com>
> ---
> drivers/block/xen-blkfront.c | 7 +++++--
> 1 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> index 429d201..dc8fe25 100644
> --- a/drivers/block/xen-blkfront.c
> +++ b/drivers/block/xen-blkfront.c
> @@ -1350,8 +1350,10 @@ static void blkif_free(struct blkfront_info *info, int suspend)
> if (info->rq)
> blk_mq_stop_hw_queues(info->rq);
>
> - for (i = 0; i < info->nr_rings; i++)
> - blkif_free_ring(&info->rinfo[i]);
> + if (info->rinfo) {
> + for (i = 0; i < info->nr_rings; i++)
> + blkif_free_ring(&info->rinfo[i]);
> + }
I don't see the point in the if case here, you already fixed it by
setting the nr_rings value which I think it's the correct way of
fixing it.
Thanks, Roger.
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [Xen-devel] [PATCH] xen-blkfront: fix kernel panic with negotiate_mq error path
2018-10-30 10:39 ` Roger Pau Monné
@ 2018-10-30 16:29 ` Manjunath Patil
0 siblings, 0 replies; 5+ messages in thread
From: Manjunath Patil @ 2018-10-30 16:29 UTC (permalink / raw)
To: Roger Pau Monné
Cc: boris.ostrovsky, jgross, konrad.wilk, axboe, xen-devel,
linux-block, linux-kernel
On 10/30/2018 3:39 AM, Roger Pau Monné wrote:
> On Mon, Oct 29, 2018 at 11:31:56AM -0700, Manjunath Patil wrote:
>> info->nr_rings isn't adjusted in case of ENOMEM error from
>> negotiate_mq(). This leads to kernel panic in error path.
>>
>> Typical call stack involving panic -
>> #8 page_fault at ffffffff8175936f
>> [exception RIP: blkif_free_ring+33]
>> RIP: ffffffffa0149491 RSP: ffff8804f7673c08 RFLAGS: 00010292
>> ...
>> #9 blkif_free at ffffffffa0149aaa [xen_blkfront]
>> #10 talk_to_blkback at ffffffffa014c8cd [xen_blkfront]
>> #11 blkback_changed at ffffffffa014ea8b [xen_blkfront]
>> #12 xenbus_otherend_changed at ffffffff81424670
>> #13 backend_changed at ffffffff81426dc3
>> #14 xenwatch_thread at ffffffff81422f29
>> #15 kthread at ffffffff810abe6a
>> #16 ret_from_fork at ffffffff81754078
>>
>> Though either of my changes avoid the panic, I included both the
>> changes. This issue got introduced with "7ed8ce1 xen-blkfront: move
>> negotiate_mq to cover all cases of new VBDs"
>>
>> Signed-off-by: Manjunath Patil <manjunath.b.patil@oracle.com>
>> ---
>> drivers/block/xen-blkfront.c | 7 +++++--
>> 1 files changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
>> index 429d201..dc8fe25 100644
>> --- a/drivers/block/xen-blkfront.c
>> +++ b/drivers/block/xen-blkfront.c
>> @@ -1350,8 +1350,10 @@ static void blkif_free(struct blkfront_info *info, int suspend)
>> if (info->rq)
>> blk_mq_stop_hw_queues(info->rq);
>>
>> - for (i = 0; i < info->nr_rings; i++)
>> - blkif_free_ring(&info->rinfo[i]);
>> + if (info->rinfo) {
>> + for (i = 0; i < info->nr_rings; i++)
>> + blkif_free_ring(&info->rinfo[i]);
>> + }
> I don't see the point in the if case here, you already fixed it by
> setting the nr_rings value which I think it's the correct way of
> fixing it.
>
> Thanks, Roger.
Thank you Roger for your comments.
I will exclude this change and send for review again.
-Thanks,
Manjunath
^ permalink raw reply [flat|nested] 5+ messages in thread
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2018-10-29 18:31 [PATCH] xen-blkfront: fix kernel panic with negotiate_mq error path Manjunath Patil
2018-10-30 7:04 ` Juergen Gross
2018-10-30 16:27 ` [Xen-devel] " Manjunath Patil
2018-10-30 10:39 ` Roger Pau Monné
2018-10-30 16:29 ` [Xen-devel] " Manjunath Patil
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