2019-01-07 09:57:28

by Vivek Gautam

[permalink] [raw]
Subject: [PATCH 1/1] drm/prime: Use sg_dma_len() macro to get sg's length

After mapping a sg list we should use sg_dma_address(), and
sg_dma_len() macros to access sg->address and sg->length. Fix
the same for sg->length in drm_prime_sg_to_page_addr_arrays().

Signed-off-by: Vivek Gautam <[email protected]>
---

This came while debugging one dmabuf import issue that we are seeing
on sdm845 target.
The dmabuf which is prepared by video (venus in this case), is imported
by drm device.
The import call flow looks like follows:

drm_gem_prime_import()
- drm_gem_prime_import_dev()
- dma_buf_attach() & dma_buf_map_attachment()
- From dma_buf_map_attachment()
- vb2_dma_sg_dmabuf_ops_map()
- dma_map_sg(): this updates the sg->nents.

From debugging, the sg table mapping results in sg's 'nents' to be less that
the original nents. Now drm device prepares the page information based on
this sg table, and messes up with the mappings, and we start seeing random
crashes as below from drm's memory space.

Although this change isn't helping to fix the issue currently, but
this fix seems the right thing to do.

One thing to notice is that, if we restore the sg->nents to
sg->orig_nents in vb2_dma_sg_dmabuf_ops_map(), we don't see the below
corruptions.

Any pointers on this will be highly appreciated.
Thanks.

------
[ 338.070558] Unable to handle kernel paging request at virtual address 0000400000000038
[ 338.078751] Mem abort info:
[ 338.081671] ESR = 0x96000004
[ 338.084860] Exception class = DABT (current EL), IL = 32 bits
[ 338.090972] SET = 0, FnV = 0
[ 338.094139] EA = 0, S1PTW = 0
[ 338.097393] Data abort info:
[ 338.100375] ISV = 0, ISS = 0x00000004
[ 338.104362] CM = 0, WnR = 0
[ 338.107446] [0000400000000038] address between user and kernel address ranges
[ 338.114801] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[ 338.120527] Modules linked in: rfcomm uinput cdc_ether venus_dec venus_enc usbnet videobuf2_dma_sg videobuf2_memops hci_uart btqca bluetooth r8152 mii ath10k_snoc venus_core ath10k_core v4l2_mem2mem videobuf2_v4l2 videobuf2_common ath mac80211 ecdh_generic qcom_q6v5_mss lzo lzo_compress qcom_q6v5_adsp qcom_common qcom_q6v5 zram bridge stp llc ipt_MASQUERADE fuse snd_seq_dummy snd_seq snd_seq_device cfg80211 joydev
[ 338.158192] CPU: 4 PID: 3235 Comm: chrome Tainted: G W 4.19.0 #2
[ 338.165700] Hardware name: Google Cheza (rev1) (DT)
[ 338.170720] pstate: 80400009 (Nzcv daif +PAN -UAO)
[ 338.175660] pc : drm_mm_insert_node_in_range+0xfc/0x348
[ 338.181035] lr : drm_mm_insert_node_in_range+0x24/0x348
[ 338.186407] sp : ffffff8013033b30
[ 338.189816] x29: ffffff8013033bd0 x28: ffffff8008591894
[ 338.195275] x27: 0000000000000010 x26: 0000000000000000
[ 338.200734] x25: 0000000000000000 x24: ffffffffffffffff
[ 338.206194] x23: 0000000000000000 x22: ffffffc0f48b7e08
[ 338.211656] x21: 0000000000000000 x20: 000000000000005d
[ 338.217118] x19: 0000000000000000 x18: 0000000000000000
[ 338.222581] x17: 0000000000000000 x16: 0000000000000000
[ 338.228046] x15: 0000000000000000 x14: 0000000000000000
[ 338.233511] x13: 0000000000000001 x12: ffffffc0b1da7200
[ 338.238978] x11: 0000000000000010 x10: 0000000000000010
[ 338.244437] x9 : 0000000000000008 x8 : 0000400000000000
[ 338.249898] x7 : 0000000000000000 x6 : ffffffffffffffff
[ 338.255361] x5 : 0000000000000000 x4 : 0000000000000000
[ 338.260823] x3 : 0000000000000000 x2 : 000000000000005d
[ 338.266285] x1 : ffffffc0b1da7100 x0 : ffffffc0b0215800
[ 338.271748] Process chrome (pid: 3235, stack limit = 0x000000000900f416)
[ 338.278628] Call trace:
[ 338.281151] drm_mm_insert_node_in_range+0xfc/0x348
[ 338.286168] msm_gem_map_vma+0x60/0xdc
[ 338.290022] msm_gem_get_iova+0xb4/0xf4
[ 338.293967] msm_ioctl_gem_info+0x90/0xdc
[ 338.298089] drm_ioctl_kernel+0xa8/0xe8
[ 338.302043] drm_ioctl+0x218/0x384
[ 338.305547] drm_compat_ioctl+0xd8/0xe8
[ 338.309503] __arm64_compat_sys_ioctl+0x134/0x20c
[ 338.314339] el0_svc_common+0xa0/0xf0
[ 338.318108] el0_svc_compat_handler+0x2c/0x38
[ 338.322588] el0_svc_compat+0x8/0x18
[ 338.326274] Code: f94066c8 aa1f03e0 321d03e9 321c03ea (f9401d0b)
[ 338.332538] ---[ end trace 5c09e60869887d87 ]---
[ 338.354633] Kernel panic - not syncing: Fatal exception
[ 338.360018] SMP: stopping secondary CPUs
[ 338.364179] Kernel Offset: disabled
[ 338.367779] CPU features: 0x0,22802a18
[ 338.371643] Memory Limit: none
------

drivers/gpu/drm/drm_prime.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 231e3f6d5f41..0d9b1c43523a 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -945,7 +945,7 @@ int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,

index = 0;
for_each_sg(sgt->sgl, sg, sgt->nents, count) {
- len = sg->length;
+ len = sg_dma_length(sg);
page = sg_page(sg);
addr = sg_dma_address(sg);

--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation



2019-01-07 10:46:08

by kernel test robot

[permalink] [raw]
Subject: Re: [PATCH 1/1] drm/prime: Use sg_dma_len() macro to get sg's length

Hi Vivek,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v5.0-rc1 next-20190107]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Vivek-Gautam/drm-prime-Use-sg_dma_len-macro-to-get-sg-s-length/20190107-181350
config: x86_64-randconfig-x013-201901 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64

All errors (new ones prefixed by >>):

drivers/gpu/drm/drm_prime.c: In function 'drm_prime_sg_to_page_addr_arrays':
>> drivers/gpu/drm/drm_prime.c:948:9: error: implicit declaration of function 'sg_dma_length'; did you mean 'sg_dma_len'? [-Werror=implicit-function-declaration]
len = sg_dma_length(sg);
^~~~~~~~~~~~~
sg_dma_len
cc1: some warnings being treated as errors

vim +948 drivers/gpu/drm/drm_prime.c

926
927 /**
928 * drm_prime_sg_to_page_addr_arrays - convert an sg table into a page array
929 * @sgt: scatter-gather table to convert
930 * @pages: optional array of page pointers to store the page array in
931 * @addrs: optional array to store the dma bus address of each page
932 * @max_entries: size of both the passed-in arrays
933 *
934 * Exports an sg table into an array of pages and addresses. This is currently
935 * required by the TTM driver in order to do correct fault handling.
936 */
937 int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
938 dma_addr_t *addrs, int max_entries)
939 {
940 unsigned count;
941 struct scatterlist *sg;
942 struct page *page;
943 u32 len, index;
944 dma_addr_t addr;
945
946 index = 0;
947 for_each_sg(sgt->sgl, sg, sgt->nents, count) {
> 948 len = sg_dma_length(sg);
949 page = sg_page(sg);
950 addr = sg_dma_address(sg);
951
952 while (len > 0) {
953 if (WARN_ON(index >= max_entries))
954 return -1;
955 if (pages)
956 pages[index] = page;
957 if (addrs)
958 addrs[index] = addr;
959
960 page++;
961 addr += PAGE_SIZE;
962 len -= PAGE_SIZE;
963 index++;
964 }
965 }
966 return 0;
967 }
968 EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays);
969

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation


Attachments:
(No filename) (2.62 kB)
.config.gz (26.43 kB)
Download all attachments

2019-01-07 11:26:44

by Vivek Gautam

[permalink] [raw]
Subject: Re: [PATCH 1/1] drm/prime: Use sg_dma_len() macro to get sg's length

On Mon, Jan 7, 2019 at 4:14 PM kbuild test robot <[email protected]> wrote:
>
> Hi Vivek,
>
> Thank you for the patch! Yet something to improve:
>
> [auto build test ERROR on linus/master]
> [also build test ERROR on v5.0-rc1 next-20190107]
> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
>
> url: https://github.com/0day-ci/linux/commits/Vivek-Gautam/drm-prime-Use-sg_dma_len-macro-to-get-sg-s-length/20190107-181350
> config: x86_64-randconfig-x013-201901 (attached as .config)
> compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
> reproduce:
> # save the attached .config to linux build tree
> make ARCH=x86_64
>
> All errors (new ones prefixed by >>):
>
> drivers/gpu/drm/drm_prime.c: In function 'drm_prime_sg_to_page_addr_arrays':
> >> drivers/gpu/drm/drm_prime.c:948:9: error: implicit declaration of function 'sg_dma_length'; did you mean 'sg_dma_len'? [-Werror=implicit-function-declaration]
> len = sg_dma_length(sg);
> ^~~~~~~~~~~~~
> sg_dma_len

Sorry, my fat finger :(
This should be as suggested - sg_dma_len().

Thanks
Vivek

> cc1: some warnings being treated as errors
>
> vim +948 drivers/gpu/drm/drm_prime.c
>
> 926
> 927 /**
> 928 * drm_prime_sg_to_page_addr_arrays - convert an sg table into a page array
> 929 * @sgt: scatter-gather table to convert
> 930 * @pages: optional array of page pointers to store the page array in
> 931 * @addrs: optional array to store the dma bus address of each page
> 932 * @max_entries: size of both the passed-in arrays
> 933 *
> 934 * Exports an sg table into an array of pages and addresses. This is currently
> 935 * required by the TTM driver in order to do correct fault handling.
> 936 */
> 937 int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
> 938 dma_addr_t *addrs, int max_entries)
> 939 {
> 940 unsigned count;
> 941 struct scatterlist *sg;
> 942 struct page *page;
> 943 u32 len, index;
> 944 dma_addr_t addr;
> 945
> 946 index = 0;
> 947 for_each_sg(sgt->sgl, sg, sgt->nents, count) {
> > 948 len = sg_dma_length(sg);
> 949 page = sg_page(sg);
> 950 addr = sg_dma_address(sg);
> 951
> 952 while (len > 0) {
> 953 if (WARN_ON(index >= max_entries))
> 954 return -1;
> 955 if (pages)
> 956 pages[index] = page;
> 957 if (addrs)
> 958 addrs[index] = addr;
> 959
> 960 page++;
> 961 addr += PAGE_SIZE;
> 962 len -= PAGE_SIZE;
> 963 index++;
> 964 }
> 965 }
> 966 return 0;
> 967 }
> 968 EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays);
> 969
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all Intel Corporation



--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation

2019-01-07 15:53:26

by Vivek Gautam

[permalink] [raw]
Subject: [PATCH v2 1/1] drm/prime: Use sg_dma_len() macro to get sg's length

After mapping a sg list the we should use sg_dma_address() and
sg_dma_len() macros to access sg->address and sg->length. Fix
the same for sg->length in drm_prime_sg_to_page_addr_arrays().

Signed-off-by: Vivek Gautam <[email protected]>
---

Changes since v1:
- Fixed compilation error: replaced sg_dma_length() with sg_dma_len().

This came while debugging one dmabuf import issue that we are seeing
on sdm845 target.
The dmabuf which is prepared by video (venus in this case), is imported
by drm device.
The import call flow looks like follows:

drm_gem_prime_import()
- drm_gem_prime_import_dev()
- dma_buf_attach() & dma_buf_map_attachment()
- From dma_buf_map_attachment()
- vb2_dma_sg_dmabuf_ops_map()
- dma_map_sg(): this updates the sg->nents.

From debugging, the sg table mapping results in sg's 'nents' to be less that
the original nents. Now drm device prepares the page information based on
this sg table, and messes up with the mappings, and we start seeing random
crashes as below from drm's memory space.

Although this change isn't helping to fix the issue currently, but
this fix seems the right thing to do.

One thing to notice is that, if we restore the sg->nents to
sg->orig_nents in vb2_dma_sg_dmabuf_ops_map(), we don't see the below
corruptions.

Any pointers on this will be highly appreciated.
Thanks.

------
[ 338.070558] Unable to handle kernel paging request at virtual address 0000400000000038
[ 338.078751] Mem abort info:
[ 338.081671] ESR = 0x96000004
[ 338.084860] Exception class = DABT (current EL), IL = 32 bits
[ 338.090972] SET = 0, FnV = 0
[ 338.094139] EA = 0, S1PTW = 0
[ 338.097393] Data abort info:
[ 338.100375] ISV = 0, ISS = 0x00000004
[ 338.104362] CM = 0, WnR = 0
[ 338.107446] [0000400000000038] address between user and kernel address ranges
[ 338.114801] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[ 338.120527] Modules linked in: rfcomm uinput cdc_ether venus_dec venus_enc usbnet videobuf2_dma_sg videobuf2_memops hci_uart btqca bluetooth r8152 mii ath10k_snoc venus_core ath10k_core v4l2_mem2mem videobuf2_v4l2 videobuf2_common ath mac80211 ecdh_generic qcom_q6v5_mss lzo lzo_compress qcom_q6v5_adsp qcom_common qcom_q6v5 zram bridge stp llc ipt_MASQUERADE fuse snd_seq_dummy snd_seq snd_seq_device cfg80211 joydev
[ 338.158192] CPU: 4 PID: 3235 Comm: chrome Tainted: G W 4.19.0 #2
[ 338.165700] Hardware name: Google Cheza (rev1) (DT)
[ 338.170720] pstate: 80400009 (Nzcv daif +PAN -UAO)
[ 338.175660] pc : drm_mm_insert_node_in_range+0xfc/0x348
[ 338.181035] lr : drm_mm_insert_node_in_range+0x24/0x348
[ 338.186407] sp : ffffff8013033b30
[ 338.189816] x29: ffffff8013033bd0 x28: ffffff8008591894
[ 338.195275] x27: 0000000000000010 x26: 0000000000000000
[ 338.200734] x25: 0000000000000000 x24: ffffffffffffffff
[ 338.206194] x23: 0000000000000000 x22: ffffffc0f48b7e08
[ 338.211656] x21: 0000000000000000 x20: 000000000000005d
[ 338.217118] x19: 0000000000000000 x18: 0000000000000000
[ 338.222581] x17: 0000000000000000 x16: 0000000000000000
[ 338.228046] x15: 0000000000000000 x14: 0000000000000000
[ 338.233511] x13: 0000000000000001 x12: ffffffc0b1da7200
[ 338.238978] x11: 0000000000000010 x10: 0000000000000010
[ 338.244437] x9 : 0000000000000008 x8 : 0000400000000000
[ 338.249898] x7 : 0000000000000000 x6 : ffffffffffffffff
[ 338.255361] x5 : 0000000000000000 x4 : 0000000000000000
[ 338.260823] x3 : 0000000000000000 x2 : 000000000000005d
[ 338.266285] x1 : ffffffc0b1da7100 x0 : ffffffc0b0215800
[ 338.271748] Process chrome (pid: 3235, stack limit = 0x000000000900f416)
[ 338.278628] Call trace:
[ 338.281151] drm_mm_insert_node_in_range+0xfc/0x348
[ 338.286168] msm_gem_map_vma+0x60/0xdc
[ 338.290022] msm_gem_get_iova+0xb4/0xf4
[ 338.293967] msm_ioctl_gem_info+0x90/0xdc
[ 338.298089] drm_ioctl_kernel+0xa8/0xe8
[ 338.302043] drm_ioctl+0x218/0x384
[ 338.305547] drm_compat_ioctl+0xd8/0xe8
[ 338.309503] __arm64_compat_sys_ioctl+0x134/0x20c
[ 338.314339] el0_svc_common+0xa0/0xf0
[ 338.318108] el0_svc_compat_handler+0x2c/0x38
[ 338.322588] el0_svc_compat+0x8/0x18
[ 338.326274] Code: f94066c8 aa1f03e0 321d03e9 321c03ea (f9401d0b)
[ 338.332538] ---[ end trace 5c09e60869887d87 ]---
[ 338.354633] Kernel panic - not syncing: Fatal exception
[ 338.360018] SMP: stopping secondary CPUs
[ 338.364179] Kernel Offset: disabled
[ 338.367779] CPU features: 0x0,22802a18
[ 338.371643] Memory Limit: none
------

drivers/gpu/drm/drm_prime.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 231e3f6d5f41..aa87ba9c0d7b 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -945,7 +945,7 @@ int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,

index = 0;
for_each_sg(sgt->sgl, sg, sgt->nents, count) {
- len = sg->length;
+ len = sg_dma_len(sg);
page = sg_page(sg);
addr = sg_dma_address(sg);

--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation


2019-01-07 17:38:34

by Daniel Vetter

[permalink] [raw]
Subject: Re: [PATCH v2 1/1] drm/prime: Use sg_dma_len() macro to get sg's length

On Mon, Jan 07, 2019 at 05:37:08PM +0530, Vivek Gautam wrote:
> After mapping a sg list the we should use sg_dma_address() and
> sg_dma_len() macros to access sg->address and sg->length. Fix
> the same for sg->length in drm_prime_sg_to_page_addr_arrays().
>
> Signed-off-by: Vivek Gautam <[email protected]>
> ---
>
> Changes since v1:
> - Fixed compilation error: replaced sg_dma_length() with sg_dma_len().
>
> This came while debugging one dmabuf import issue that we are seeing
> on sdm845 target.
> The dmabuf which is prepared by video (venus in this case), is imported
> by drm device.
> The import call flow looks like follows:
>
> drm_gem_prime_import()
> - drm_gem_prime_import_dev()
> - dma_buf_attach() & dma_buf_map_attachment()
> - From dma_buf_map_attachment()
> - vb2_dma_sg_dmabuf_ops_map()
> - dma_map_sg(): this updates the sg->nents.
>
> From debugging, the sg table mapping results in sg's 'nents' to be less that
> the original nents. Now drm device prepares the page information based on
> this sg table, and messes up with the mappings, and we start seeing random
> crashes as below from drm's memory space.
>
> Although this change isn't helping to fix the issue currently, but
> this fix seems the right thing to do.
>
> One thing to notice is that, if we restore the sg->nents to
> sg->orig_nents in vb2_dma_sg_dmabuf_ops_map(), we don't see the below
> corruptions.
>
> Any pointers on this will be highly appreciated.
> Thanks.
>
> ------
> [ 338.070558] Unable to handle kernel paging request at virtual address 0000400000000038
> [ 338.078751] Mem abort info:
> [ 338.081671] ESR = 0x96000004
> [ 338.084860] Exception class = DABT (current EL), IL = 32 bits
> [ 338.090972] SET = 0, FnV = 0
> [ 338.094139] EA = 0, S1PTW = 0
> [ 338.097393] Data abort info:
> [ 338.100375] ISV = 0, ISS = 0x00000004
> [ 338.104362] CM = 0, WnR = 0
> [ 338.107446] [0000400000000038] address between user and kernel address ranges
> [ 338.114801] Internal error: Oops: 96000004 [#1] PREEMPT SMP
> [ 338.120527] Modules linked in: rfcomm uinput cdc_ether venus_dec venus_enc usbnet videobuf2_dma_sg videobuf2_memops hci_uart btqca bluetooth r8152 mii ath10k_snoc venus_core ath10k_core v4l2_mem2mem videobuf2_v4l2 videobuf2_common ath mac80211 ecdh_generic qcom_q6v5_mss lzo lzo_compress qcom_q6v5_adsp qcom_common qcom_q6v5 zram bridge stp llc ipt_MASQUERADE fuse snd_seq_dummy snd_seq snd_seq_device cfg80211 joydev
> [ 338.158192] CPU: 4 PID: 3235 Comm: chrome Tainted: G W 4.19.0 #2
> [ 338.165700] Hardware name: Google Cheza (rev1) (DT)
> [ 338.170720] pstate: 80400009 (Nzcv daif +PAN -UAO)
> [ 338.175660] pc : drm_mm_insert_node_in_range+0xfc/0x348
> [ 338.181035] lr : drm_mm_insert_node_in_range+0x24/0x348
> [ 338.186407] sp : ffffff8013033b30
> [ 338.189816] x29: ffffff8013033bd0 x28: ffffff8008591894
> [ 338.195275] x27: 0000000000000010 x26: 0000000000000000
> [ 338.200734] x25: 0000000000000000 x24: ffffffffffffffff
> [ 338.206194] x23: 0000000000000000 x22: ffffffc0f48b7e08
> [ 338.211656] x21: 0000000000000000 x20: 000000000000005d
> [ 338.217118] x19: 0000000000000000 x18: 0000000000000000
> [ 338.222581] x17: 0000000000000000 x16: 0000000000000000
> [ 338.228046] x15: 0000000000000000 x14: 0000000000000000
> [ 338.233511] x13: 0000000000000001 x12: ffffffc0b1da7200
> [ 338.238978] x11: 0000000000000010 x10: 0000000000000010
> [ 338.244437] x9 : 0000000000000008 x8 : 0000400000000000
> [ 338.249898] x7 : 0000000000000000 x6 : ffffffffffffffff
> [ 338.255361] x5 : 0000000000000000 x4 : 0000000000000000
> [ 338.260823] x3 : 0000000000000000 x2 : 000000000000005d
> [ 338.266285] x1 : ffffffc0b1da7100 x0 : ffffffc0b0215800
> [ 338.271748] Process chrome (pid: 3235, stack limit = 0x000000000900f416)
> [ 338.278628] Call trace:
> [ 338.281151] drm_mm_insert_node_in_range+0xfc/0x348
> [ 338.286168] msm_gem_map_vma+0x60/0xdc
> [ 338.290022] msm_gem_get_iova+0xb4/0xf4
> [ 338.293967] msm_ioctl_gem_info+0x90/0xdc
> [ 338.298089] drm_ioctl_kernel+0xa8/0xe8
> [ 338.302043] drm_ioctl+0x218/0x384
> [ 338.305547] drm_compat_ioctl+0xd8/0xe8
> [ 338.309503] __arm64_compat_sys_ioctl+0x134/0x20c
> [ 338.314339] el0_svc_common+0xa0/0xf0
> [ 338.318108] el0_svc_compat_handler+0x2c/0x38
> [ 338.322588] el0_svc_compat+0x8/0x18
> [ 338.326274] Code: f94066c8 aa1f03e0 321d03e9 321c03ea (f9401d0b)
> [ 338.332538] ---[ end trace 5c09e60869887d87 ]---
> [ 338.354633] Kernel panic - not syncing: Fatal exception
> [ 338.360018] SMP: stopping secondary CPUs
> [ 338.364179] Kernel Offset: disabled
> [ 338.367779] CPU features: 0x0,22802a18
> [ 338.371643] Memory Limit: none
> ------
>
> drivers/gpu/drm/drm_prime.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index 231e3f6d5f41..aa87ba9c0d7b 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -945,7 +945,7 @@ int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
>
> index = 0;
> for_each_sg(sgt->sgl, sg, sgt->nents, count) {

I thought Christoph is creating a new macro to iterator over the mapped
sg, which needs to be used here instead of for_each_sg (which is only
valid for iterating over the cpu side mapping/struct page).
-Daniel
> - len = sg->length;
> + len = sg_dma_len(sg);
> page = sg_page(sg);
> addr = sg_dma_address(sg);
>
> --
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> of Code Aurora Forum, hosted by The Linux Foundation
>

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch