2022-07-08 16:51:05

by Demi Marie Obenour

Subject: gntdev warning fixes

The recent gntdev fixes introduced two incorrect WARN_ON()s, which
triggered immediately on my system. Patches for master and all
supported stable versions follow.

2022-07-08 16:51:11

by Demi Marie Obenour

Subject: [PATCH 4.19] Ignore failure to unmap -1

The error paths of gntdev_mmap() can call unmap_grant_pages() even
though not all of the pages have been successfully mapped. This will
trigger the WARN_ON()s in __unmap_grant_pages_done(). The number of
warnings can be very large; I have observed thousands of lines of
warnings in the systemd journal.

Avoid this problem by only warning on unmapping failure if the handle
being unmapped is not -1. The handle field of any page that was not
successfully mapped will be -1, so this catches all cases wherr
unmapping can legitimately fail.

Suggested-by: Juergen Gross <[email protected]>
Cc: [email protected]
Signed-off-by: Demi Marie Obenour <[email protected]>
Fixes: 73e9e72247b9 ("xen/gntdev: Avoid blocking in unmap_grant_pages()")
---
drivers/xen/gntdev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 492084814f55d8ed46d2d656db75b28a91dd7f06..27d955c5d9f9076266f77b9fedfa1a6a2ba08f56 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -416,7 +416,8 @@ static void __unmap_grant_pages_done(int result,
unsigned int offset = data->unmap_ops - map->unmap_ops;

for (i = 0; i < data->count; i++) {
- WARN_ON(map->unmap_ops[offset+i].status);
+ WARN_ON(map->unmap_ops[offset+i].status &&
+ map->unmap_ops[offset+i].handle != -1);
pr_debug("unmap handle=%d st=%d\n",
map->unmap_ops[offset+i].handle,
map->unmap_ops[offset+i].status);
--
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab

2022-07-08 16:51:21

by Demi Marie Obenour

Subject: [PATCH 5.10] Ignore failure to unmap -1

The error paths of gntdev_mmap() can call unmap_grant_pages() even
though not all of the pages have been successfully mapped. This will
trigger the WARN_ON()s in __unmap_grant_pages_done(). The number of
warnings can be very large; I have observed thousands of lines of
warnings in the systemd journal.

Avoid this problem by only warning on unmapping failure if the handle
being unmapped is not -1. The handle field of any page that was not
successfully mapped will be -1, so this catches all cases where
unmapping can legitimately fail.

Suggested-by: Juergen Gross <[email protected]>
Cc: [email protected]
Signed-off-by: Demi Marie Obenour <[email protected]>
Fixes: 79963021fd71 ("xen/gntdev: Avoid blocking in unmap_grant_pages()")
---
drivers/xen/gntdev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index f415c056ff8ab8d808ee2bacfaa3cad57af28204..54fee4087bf1078803c230ad2081aafa8415cf53 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -401,7 +401,8 @@ static void __unmap_grant_pages_done(int result,
unsigned int offset = data->unmap_ops - map->unmap_ops;

for (i = 0; i < data->count; i++) {
- WARN_ON(map->unmap_ops[offset+i].status);
+ WARN_ON(map->unmap_ops[offset+i].status &&
+ map->unmap_ops[offset+i].handle != -1);
pr_debug("unmap handle=%d st=%d\n",
map->unmap_ops[offset+i].handle,
map->unmap_ops[offset+i].status);
--
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab

2022-07-08 16:51:26

by Demi Marie Obenour

Subject: [PATCH 5.4] Ignore failure to unmap -1

The error paths of gntdev_mmap() can call unmap_grant_pages() even
though not all of the pages have been successfully mapped. This will
trigger the WARN_ON()s in __unmap_grant_pages_done(). The number of
warnings can be very large; I have observed thousands of lines of
warnings in the systemd journal.

Avoid this problem by only warning on unmapping failure if the handle
being unmapped is not -1. The handle field of any page that was not
successfully mapped will be -1, so this catches all cases wherr
unmapping can legitimately fail.

Suggested-by: Juergen Gross <[email protected]>
Cc: [email protected]
Signed-off-by: Demi Marie Obenour <[email protected]>
Fixes: ee25841221c1 ("xen/gntdev: Avoid blocking in unmap_grant_pages()")
---
drivers/xen/gntdev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index f464793477650e631c8928e85c1990c5964c2e94..bba849e5d8a7b4d54925b842fbe3c6792e0f0214 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -413,7 +413,8 @@ static void __unmap_grant_pages_done(int result,
unsigned int offset = data->unmap_ops - map->unmap_ops;

for (i = 0; i < data->count; i++) {
- WARN_ON(map->unmap_ops[offset+i].status);
+ WARN_ON(map->unmap_ops[offset+i].status &&
+ map->unmap_ops[offset+i].handle != -1);
pr_debug("unmap handle=%d st=%d\n",
map->unmap_ops[offset+i].handle,
map->unmap_ops[offset+i].status);
--
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab

2022-07-08 16:51:35

by Demi Marie Obenour

Subject: [PATCH 5.18] Ignore failure to unmap INVALID_GRANT_HANDLE

The error paths of gntdev_mmap() can call unmap_grant_pages() even
though not all of the pages have been successfully mapped. This will
trigger the WARN_ON()s in __unmap_grant_pages_done(). The number of
warnings can be very large; I have observed thousands of lines of
warnings in the systemd journal.

Avoid this problem by only warning on unmapping failure if the handle
being unmapped is not INVALID_GRANT_HANDLE. The handle field of any
page that was not successfully mapped will be INVALID_GRANT_HANDLE, so
this catches all cases where unmapping can legitimately fail.

Suggested-by: Juergen Gross <[email protected]>
Cc: [email protected]
Signed-off-by: Demi Marie Obenour <[email protected]>
Fixes: d4a49d20cd7c ("xen/gntdev: Avoid blocking in unmap_grant_pages()")
---
drivers/xen/gntdev.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 4b56c39f766d4da68570d08d963f6ef40c8d9c37..22fcd503f4a4487d0aed147c94f432683dad8c73 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -396,13 +396,17 @@ static void __unmap_grant_pages_done(int result,
unsigned int offset = data->unmap_ops - map->unmap_ops;

for (i = 0; i < data->count; i++) {
- WARN_ON(map->unmap_ops[offset+i].status);
+ WARN_ON(map->unmap_ops[offset+i].status &&
+ map->unmap_ops[offset+i].handle !=
+ INVALID_GRANT_HANDLE);
pr_debug("unmap handle=%d st=%d\n",
map->unmap_ops[offset+i].handle,
map->unmap_ops[offset+i].status);
map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
if (use_ptemod) {
- WARN_ON(map->kunmap_ops[offset+i].status);
+ WARN_ON(map->kunmap_ops[offset+i].status &&
+ map->kunmap_ops[offset+i].handle !=
+ INVALID_GRANT_HANDLE);
pr_debug("kunmap handle=%u st=%d\n",
map->kunmap_ops[offset+i].handle,
map->kunmap_ops[offset+i].status);
--
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab

2022-07-08 16:51:36

by Demi Marie Obenour

Subject: [PATCH 5.15] Ignore failure to unmap INVALID_GRANT_HANDLE

The error paths of gntdev_mmap() can call unmap_grant_pages() even
though not all of the pages have been successfully mapped. This will
trigger the WARN_ON()s in __unmap_grant_pages_done(). The number of
warnings can be very large; I have observed thousands of lines of
warnings in the systemd journal.

Avoid this problem by only warning on unmapping failure if the handle
being unmapped is not INVALID_GRANT_HANDLE. The handle field of any
page that was not successfully mapped will be INVALID_GRANT_HANDLE, so
this catches all cases where unmapping can legitimately fail.

Suggested-by: Juergen Gross <[email protected]>
Cc: [email protected]
Signed-off-by: Demi Marie Obenour <[email protected]>
Fixes: 87a54feba68f ("xen/gntdev: Avoid blocking in unmap_grant_pages()")
---
drivers/xen/gntdev.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 4b56c39f766d4da68570d08d963f6ef40c8d9c37..22fcd503f4a4487d0aed147c94f432683dad8c73 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -396,13 +396,17 @@ static void __unmap_grant_pages_done(int result,
unsigned int offset = data->unmap_ops - map->unmap_ops;

for (i = 0; i < data->count; i++) {
- WARN_ON(map->unmap_ops[offset+i].status);
+ WARN_ON(map->unmap_ops[offset+i].status &&
+ map->unmap_ops[offset+i].handle !=
+ INVALID_GRANT_HANDLE);
pr_debug("unmap handle=%d st=%d\n",
map->unmap_ops[offset+i].handle,
map->unmap_ops[offset+i].status);
map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
if (use_ptemod) {
- WARN_ON(map->kunmap_ops[offset+i].status);
+ WARN_ON(map->kunmap_ops[offset+i].status &&
+ map->kunmap_ops[offset+i].handle !=
+ INVALID_GRANT_HANDLE);
pr_debug("kunmap handle=%u st=%d\n",
map->kunmap_ops[offset+i].handle,
map->kunmap_ops[offset+i].status);
--
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab

2022-07-08 16:53:22

by Demi Marie Obenour

Subject: [PATCH 4.14] Ignore failure to unmap -1

The error paths of gntdev_mmap() can call unmap_grant_pages() even
though not all of the pages have been successfully mapped. This will
trigger the WARN_ON()s in __unmap_grant_pages_done(). The number of
warnings can be very large; I have observed thousands of lines of
warnings in the systemd journal.

Avoid this problem by only warning on unmapping failure if the handle
being unmapped is not -1. The handle field of any page that was not
successfully mapped will be -1, so this catches all cases wherr
unmapping can legitimately fail.

Suggested-by: Juergen Gross <[email protected]>
Cc: [email protected]
Signed-off-by: Demi Marie Obenour <[email protected]>
Fixes: 2fe26a9a7048 ("xen/gntdev: Avoid blocking in unmap_grant_pages()")
---
drivers/xen/gntdev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 2827015604fbaa45f0ca60c342bbf71ce4132dec..799173755b785e2f3e2483855f75af1eba8e9373 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -393,7 +393,8 @@ static void __unmap_grant_pages_done(int result,
unsigned int offset = data->unmap_ops - map->unmap_ops;

for (i = 0; i < data->count; i++) {
- WARN_ON(map->unmap_ops[offset+i].status);
+ WARN_ON(map->unmap_ops[offset+i].status &&
+ map->unmap_ops[offset+i].handle != -1);
pr_debug("unmap handle=%d st=%d\n",
map->unmap_ops[offset+i].handle,
map->unmap_ops[offset+i].status);
--
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab

2022-07-08 17:08:26

by Demi Marie Obenour

Subject: [PATCH master] Ignore failure to unmap INVALID_GRANT_HANDLE

The error paths of gntdev_mmap() can call unmap_grant_pages() even
though not all of the pages have been successfully mapped. This will
trigger the WARN_ON()s in __unmap_grant_pages_done(). The number of
warnings can be very large; I have observed thousands of lines of
warnings in the systemd journal.

Avoid this problem by only warning on unmapping failure if the handle
being unmapped is not INVALID_GRANT_HANDLE. The handle field of any
page that was not successfully mapped will be INVALID_GRANT_HANDLE, so
this catches all cases where unmapping can legitimately fail.

Suggested-by: Juergen Gross <[email protected]>
Cc: [email protected]
Signed-off-by: Demi Marie Obenour <[email protected]>
Fixes: dbe97cff7dd9 ("xen/gntdev: Avoid blocking in unmap_grant_pages()")
---
drivers/xen/gntdev.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 4b56c39f766d4da68570d08d963f6ef40c8d9c37..22fcd503f4a4487d0aed147c94f432683dad8c73 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -396,13 +396,17 @@ static void __unmap_grant_pages_done(int result,
unsigned int offset = data->unmap_ops - map->unmap_ops;

for (i = 0; i < data->count; i++) {
- WARN_ON(map->unmap_ops[offset+i].status);
+ WARN_ON(map->unmap_ops[offset+i].status &&
+ map->unmap_ops[offset+i].handle !=
+ INVALID_GRANT_HANDLE);
pr_debug("unmap handle=%d st=%d\n",
map->unmap_ops[offset+i].handle,
map->unmap_ops[offset+i].status);
map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
if (use_ptemod) {
- WARN_ON(map->kunmap_ops[offset+i].status);
+ WARN_ON(map->kunmap_ops[offset+i].status &&
+ map->kunmap_ops[offset+i].handle !=
+ INVALID_GRANT_HANDLE);
pr_debug("kunmap handle=%u st=%d\n",
map->kunmap_ops[offset+i].handle,
map->kunmap_ops[offset+i].status);
--
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab

2022-07-09 07:01:32

by Greg Kroah-Hartman

Subject: Re: gntdev warning fixes

On Fri, Jul 08, 2022 at 12:37:44PM -0400, Demi Marie Obenour wrote:
> The recent gntdev fixes introduced two incorrect WARN_ON()s, which
> triggered immediately on my system. Patches for master and all
> supported stable versions follow.
>
>

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

2022-07-11 05:17:57

by Oleksandr Tyshchenko

Subject: Re: [PATCH master] Ignore failure to unmap INVALID_GRANT_HANDLE

On 08.07.22 19:37, Demi Marie Obenour wrote:

Hello Demi Marie


Please add subsystem to the commit subject, for example "xen/gntdev:".


> The error paths of gntdev_mmap() can call unmap_grant_pages() even
> though not all of the pages have been successfully mapped. This will
> trigger the WARN_ON()s in __unmap_grant_pages_done(). The number of
> warnings can be very large; I have observed thousands of lines of
> warnings in the systemd journal.
>
> Avoid this problem by only warning on unmapping failure if the handle
> being unmapped is not INVALID_GRANT_HANDLE. The handle field of any
> page that was not successfully mapped will be INVALID_GRANT_HANDLE, so
> this catches all cases where unmapping can legitimately fail.
>
> Suggested-by: Juergen Gross <[email protected]>
> Cc: [email protected]
> Signed-off-by: Demi Marie Obenour <[email protected]>
> Fixes: dbe97cff7dd9 ("xen/gntdev: Avoid blocking in unmap_grant_pages()")
> ---
> drivers/xen/gntdev.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index 4b56c39f766d4da68570d08d963f6ef40c8d9c37..22fcd503f4a4487d0aed147c94f432683dad8c73 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -396,13 +396,17 @@ static void __unmap_grant_pages_done(int result,
> unsigned int offset = data->unmap_ops - map->unmap_ops;
>
> for (i = 0; i < data->count; i++) {
> - WARN_ON(map->unmap_ops[offset+i].status);
> + WARN_ON(map->unmap_ops[offset+i].status &&
> + map->unmap_ops[offset+i].handle !=
> + INVALID_GRANT_HANDLE);


Nit: While extending the check I would clarify the first half of it:
"map->unmap_ops[offset+i].status != GNTST_okay"


> pr_debug("unmap handle=%d st=%d\n",
> map->unmap_ops[offset+i].handle,
> map->unmap_ops[offset+i].status);
> map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
> if (use_ptemod) {
> - WARN_ON(map->kunmap_ops[offset+i].status);
> + WARN_ON(map->kunmap_ops[offset+i].status &&
> + map->kunmap_ops[offset+i].handle !=
> + INVALID_GRANT_HANDLE);

ditto



With updated subject:

Reviewed-by: Oleksandr Tyshchenko <[email protected]>


> pr_debug("kunmap handle=%u st=%d\n",
> map->kunmap_ops[offset+i].handle,
> map->kunmap_ops[offset+i].status);

--
Regards,

Oleksandr Tyshchenko