staging: android: ion: fix page is NULL

PATCH In review Cheng Chao 2 participants 9 messages Sep 11, 2021 – Sep 23, 2021 Stable branch

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Cheng Chao

author

2021-09-11 11:21 UTC #0 lore raw

PATCH 1/1 staging: android: ion: fix page is NULL

kernel panic is here:

Unable to handle kernel paging request at virtual address b0380000
pgd = d9d94000
[b0380000] *pgd=00000000
Internal error: Oops: 2805 [#1] PREEMPT SMP ARM

...
task: daa2dd00 task.stack: da194000
PC is at v7_dma_clean_range+0x1c/0x34
LR is at arm_dma_sync_single_for_device+0x44/0x58

pc : [<c011aa0c>]    lr : [<c011645c>]    psr: 200f0013

sp : da195da0 ip : dc1f9000 fp : c1043dc4
r10: 00000000 r9 : c16f1f58 r8 : 00000001
r7 : c1621f94 r6 : c0116418 r5 : 00000000 r4 : c011aa58
r3 : 0000003f r2 : 00000040 r1 : b0480000 r0 : b0380000
Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5383d Table: 19d9406a DAC: 00000051
...
[<c011aa0c>] (v7_dma_clean_range) from [<c011645c>] (arm_dma_sync_single_for_device+0x44/0x58) [<c011645c>] (arm_dma_sync_single_for_device) from [<c0117088>] (arm_dma_sync_sg_for_device+0x50/0x7c) [<c0117088>] (arm_dma_sync_sg_for_device) from [<c0c033c4>] (ion_pages_sync_for_device+0xb0/0xec) [<c0c033c4>] (ion_pages_sync_for_device) from [<c0c054ac>] (ion_system_heap_allocate+0x2a0/0x2e0) [<c0c054ac>] (ion_system_heap_allocate) from [<c0c02c78>] (ion_alloc+0x12c/0x494) [<c0c02c78>] (ion_alloc) from [<c0c03eac>] (ion_ioctl+0x510/0x63c)
[<c0c03eac>] (ion_ioctl) from [<c027c4b0>] (do_vfs_ioctl+0xa8/0x9b4)
[<c027c4b0>] (do_vfs_ioctl) from [<c027ce28>] (SyS_ioctl+0x6c/0x7c)
[<c027ce28>] (SyS_ioctl) from [<c0108a40>] (ret_fast_syscall+0x0/0x48)

Code: e3a02004 e1a02312 e2423001 e1c00003 (ee070f3a)
---[ end trace 89278304932c0e87 ]---
Kernel panic - not syncing: Fatal exception

Signed-off-by Cheng Chao <[email protected]>

---
 drivers/staging/android/ion/ion_system_heap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

drivers/staging/android/ion/ion_system_heap.c +1 -1

index 22c481f2ae4f..2a35b99cf628 100644
@@ -75,7 +75,7 @@ static struct page *alloc_buffer_page(struct ion_system_heap *heap,
 
 	page = ion_page_pool_alloc(pool);
 
-	if (cached)
+	if (page && cached)
 		ion_pages_sync_for_device(NULL, page, PAGE_SIZE << order,
 					  DMA_BIDIRECTIONAL);
 	return page;

Signature · 1 line

2.26.3

Greg KH

maintainer

2021-09-11 11:54 UTC #1 lore raw

Quoted 52 lines · Cheng Chao

kernel panic is here:
Unable to handle kernel paging request at virtual address b0380000
pgd = d9d94000
[b0380000] *pgd=00000000
Internal error: Oops: 2805 [#1] PREEMPT SMP ARM
...
task: daa2dd00 task.stack: da194000
PC is at v7_dma_clean_range+0x1c/0x34
LR is at arm_dma_sync_single_for_device+0x44/0x58
pc : [<c011aa0c>]    lr : [<c011645c>]    psr: 200f0013
sp : da195da0 ip : dc1f9000 fp : c1043dc4
r10: 00000000 r9 : c16f1f58 r8 : 00000001
r7 : c1621f94 r6 : c0116418 r5 : 00000000 r4 : c011aa58
r3 : 0000003f r2 : 00000040 r1 : b0480000 r0 : b0380000
Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5383d Table: 19d9406a DAC: 00000051
...
[<c011aa0c>] (v7_dma_clean_range) from [<c011645c>] (arm_dma_sync_single_for_device+0x44/0x58) [<c011645c>] (arm_dma_sync_single_for_device) from [<c0117088>] (arm_dma_sync_sg_for_device+0x50/0x7c) [<c0117088>] (arm_dma_sync_sg_for_device) from [<c0c033c4>] (ion_pages_sync_for_device+0xb0/0xec) [<c0c033c4>] (ion_pages_sync_for_device) from [<c0c054ac>] (ion_system_heap_allocate+0x2a0/0x2e0) [<c0c054ac>] (ion_system_heap_allocate) from [<c0c02c78>] (ion_alloc+0x12c/0x494) [<c0c02c78>] (ion_alloc) from [<c0c03eac>] (ion_ioctl+0x510/0x63c)
[<c0c03eac>] (ion_ioctl) from [<c027c4b0>] (do_vfs_ioctl+0xa8/0x9b4)
[<c027c4b0>] (do_vfs_ioctl) from [<c027ce28>] (SyS_ioctl+0x6c/0x7c)
[<c027ce28>] (SyS_ioctl) from [<c0108a40>] (ret_fast_syscall+0x0/0x48)
Code: e3a02004 e1a02312 e2423001 e1c00003 (ee070f3a)
---[ end trace 89278304932c0e87 ]---
Kernel panic - not syncing: Fatal exception
Signed-off-by Cheng Chao <[email protected]>
---
 drivers/staging/android/ion/ion_system_heap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/staging/android/ion/ion_system_heap.c +1 -1
index 22c481f2ae4f..2a35b99cf628 100644
@@ -75,7 +75,7 @@ static struct page *alloc_buffer_page(struct ion_system_heap *heap,
 
 	page = ion_page_pool_alloc(pool);
 
-	if (cached)
+	if (page && cached)
 		ion_pages_sync_for_device(NULL, page, PAGE_SIZE << order,
 					  DMA_BIDIRECTIONAL);
 	return page;
Signature · 1 line
2.26.3

Why is this just a 4.9 patch? Ion didn't get removed until 5.11, so wouldn't this be an issue for anything 5.10 and older?

thanks,

greg k-h

Cheng Chao

author

2021-09-11 14:20 UTC #2 lore raw

for longterm v4.4.283, the code has checked if (!page)
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/staging/android/ion/ion_system_heap.c?h=v4.4.283

static struct page *alloc_buffer_page(struct ion_system_heap *heap,
struct ion_buffer *buffer,
unsigned long order)
{
...
if (!cached) {
page = ion_page_pool_alloc(pool);
} else {
...
page = alloc_pages(gfp_flags | __GFP_COMP, order);
if (!page) <---
return NULL; <---

ion_pages_sync_for_device(NULL, page, PAGE_SIZE << order,
...
}

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
for longterm v4.14.246, has no ion_pages_sync_for_device after ion_page_pool_alloc
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/staging/android/ion/ion_system_heap.c?h=v4.14.246

static struct page *alloc_buffer_page(struct ion_system_heap *heap,
struct ion_buffer *buffer,
unsigned long order)
{
...
if (!cached)
pool = heap->uncached_pools[order_to_index(order)];
else
pool = heap->cached_pools[order_to_index(order)];

page = ion_page_pool_alloc(pool);

return page;
}

----------------------------------------------------------------------------------------------------------------------------------------------------------
after longterm v4.19.206(include),

static struct page *alloc_buffer_page(struct ion_system_heap *heap,
struct ion_buffer *buffer,
unsigned long order)
{
struct ion_page_pool *pool = heap->pools[order_to_index(order)];

return ion_page_pool_alloc(pool);
}

Quoted 61 lines · Greg KH

Quoted 50 lines · Cheng Chao
kernel panic is here:
Unable to handle kernel paging request at virtual address b0380000
pgd = d9d94000
[b0380000] *pgd=00000000
Internal error: Oops: 2805 [#1] PREEMPT SMP ARM
...
task: daa2dd00 task.stack: da194000
PC is at v7_dma_clean_range+0x1c/0x34
LR is at arm_dma_sync_single_for_device+0x44/0x58
pc : [<c011aa0c>]    lr : [<c011645c>]    psr: 200f0013
sp : da195da0 ip : dc1f9000 fp : c1043dc4
r10: 00000000 r9 : c16f1f58 r8 : 00000001
r7 : c1621f94 r6 : c0116418 r5 : 00000000 r4 : c011aa58
r3 : 0000003f r2 : 00000040 r1 : b0480000 r0 : b0380000
Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5383d Table: 19d9406a DAC: 00000051
...
[<c011aa0c>] (v7_dma_clean_range) from [<c011645c>] (arm_dma_sync_single_for_device+0x44/0x58) [<c011645c>] (arm_dma_sync_single_for_device) from [<c0117088>] (arm_dma_sync_sg_for_device+0x50/0x7c) [<c0117088>] (arm_dma_sync_sg_for_device) from [<c0c033c4>] (ion_pages_sync_for_device+0xb0/0xec) [<c0c033c4>] (ion_pages_sync_for_device) from [<c0c054ac>] (ion_system_heap_allocate+0x2a0/0x2e0) [<c0c054ac>] (ion_system_heap_allocate) from [<c0c02c78>] (ion_alloc+0x12c/0x494) [<c0c02c78>] (ion_alloc) from [<c0c03eac>] (ion_ioctl+0x510/0x63c)
[<c0c03eac>] (ion_ioctl) from [<c027c4b0>] (do_vfs_ioctl+0xa8/0x9b4)
[<c027c4b0>] (do_vfs_ioctl) from [<c027ce28>] (SyS_ioctl+0x6c/0x7c)
[<c027ce28>] (SyS_ioctl) from [<c0108a40>] (ret_fast_syscall+0x0/0x48)
Code: e3a02004 e1a02312 e2423001 e1c00003 (ee070f3a)
---[ end trace 89278304932c0e87 ]---
Kernel panic - not syncing: Fatal exception
Signed-off-by Cheng Chao <[email protected]>
---
 drivers/staging/android/ion/ion_system_heap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/staging/android/ion/ion_system_heap.c +1 -2
index 22c481f2ae4f..2a35b99cf628 100644
@@ -75,7 +75,7 @@ static struct page *alloc_buffer_page(struct ion_system_heap *heap,
 
      page = ion_page_pool_alloc(pool);
 
-     if (cached)
+     if (page && cached)
              ion_pages_sync_for_device(NULL, page, PAGE_SIZE << order,
                                        DMA_BIDIRECTIONAL);
      return page;
--
Quoted 2 lines
2.26.3
Why is this just a 4.9 patch? Ion didn't get removed until 5.11, so wouldn't this be an issue for anything 5.10 and older?
thanks,
greg k-h

Cheng Chao

author

2021-09-11 14:41 UTC #3 lore raw

the bug has been introduced by the patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/drivers/staging/android/ion/ion_system_heap.c?h=v4.9.282&id=e7f63771b60e7802c5a9b437c5ab1a8e33a0bb35

Quoted 117 lines · Cheng Chao

for longterm v4.4.283, the code has checked if (!page)
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/staging/android/ion/ion_system_heap.c?h=v4.4.283
static struct page *alloc_buffer_page(struct ion_system_heap *heap,
struct ion_buffer *buffer,
unsigned long order)
{
...
if (!cached) {
page = ion_page_pool_alloc(pool);
} else {
...
page = alloc_pages(gfp_flags | __GFP_COMP, order);
if (!page) <---
return NULL; <---
ion_pages_sync_for_device(NULL, page, PAGE_SIZE << order,
...
}
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
for longterm v4.14.246, has no ion_pages_sync_for_device after ion_page_pool_alloc
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/staging/android/ion/ion_system_heap.c?h=v4.14.246
static struct page *alloc_buffer_page(struct ion_system_heap *heap,
struct ion_buffer *buffer,
unsigned long order)
{
...
if (!cached)
pool = heap->uncached_pools[order_to_index(order)];
else
pool = heap->cached_pools[order_to_index(order)];
page = ion_page_pool_alloc(pool);
return page;
}
----------------------------------------------------------------------------------------------------------------------------------------------------------
after longterm v4.19.206(include),
static struct page *alloc_buffer_page(struct ion_system_heap *heap,
struct ion_buffer *buffer,
unsigned long order)
{
struct ion_page_pool *pool = heap->pools[order_to_index(order)];
return ion_page_pool_alloc(pool);
}
Quoted 61 lines · Greg KH
Quoted 50 lines · Cheng Chao
kernel panic is here:
Unable to handle kernel paging request at virtual address b0380000
pgd = d9d94000
[b0380000] *pgd=00000000
Internal error: Oops: 2805 [#1] PREEMPT SMP ARM
...
task: daa2dd00 task.stack: da194000
PC is at v7_dma_clean_range+0x1c/0x34
LR is at arm_dma_sync_single_for_device+0x44/0x58
pc : [<c011aa0c>]    lr : [<c011645c>]    psr: 200f0013
sp : da195da0 ip : dc1f9000 fp : c1043dc4
r10: 00000000 r9 : c16f1f58 r8 : 00000001
r7 : c1621f94 r6 : c0116418 r5 : 00000000 r4 : c011aa58
r3 : 0000003f r2 : 00000040 r1 : b0480000 r0 : b0380000
Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5383d Table: 19d9406a DAC: 00000051
...
[<c011aa0c>] (v7_dma_clean_range) from [<c011645c>] (arm_dma_sync_single_for_device+0x44/0x58) [<c011645c>] (arm_dma_sync_single_for_device) from [<c0117088>] (arm_dma_sync_sg_for_device+0x50/0x7c) [<c0117088>] (arm_dma_sync_sg_for_device) from [<c0c033c4>] (ion_pages_sync_for_device+0xb0/0xec) [<c0c033c4>] (ion_pages_sync_for_device) from [<c0c054ac>] (ion_system_heap_allocate+0x2a0/0x2e0) [<c0c054ac>] (ion_system_heap_allocate) from [<c0c02c78>] (ion_alloc+0x12c/0x494) [<c0c02c78>] (ion_alloc) from [<c0c03eac>] (ion_ioctl+0x510/0x63c)
[<c0c03eac>] (ion_ioctl) from [<c027c4b0>] (do_vfs_ioctl+0xa8/0x9b4)
[<c027c4b0>] (do_vfs_ioctl) from [<c027ce28>] (SyS_ioctl+0x6c/0x7c)
[<c027ce28>] (SyS_ioctl) from [<c0108a40>] (ret_fast_syscall+0x0/0x48)
Code: e3a02004 e1a02312 e2423001 e1c00003 (ee070f3a)
---[ end trace 89278304932c0e87 ]---
Kernel panic - not syncing: Fatal exception
Signed-off-by Cheng Chao <[email protected]>
---
 drivers/staging/android/ion/ion_system_heap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/staging/android/ion/ion_system_heap.c +1 -2
index 22c481f2ae4f..2a35b99cf628 100644
@@ -75,7 +75,7 @@ static struct page *alloc_buffer_page(struct ion_system_heap *heap,
 
      page = ion_page_pool_alloc(pool);
 
-     if (cached)
+     if (page && cached)
              ion_pages_sync_for_device(NULL, page, PAGE_SIZE << order,
                                        DMA_BIDIRECTIONAL);
      return page;
--
Quoted 2 lines
2.26.3
Why is this just a 4.9 patch? Ion didn't get removed until 5.11, so wouldn't this be an issue for anything 5.10 and older?
thanks,
greg k-h

Cheng Chao

author

2021-09-22 12:17 UTC #4 lore raw

I notice that v4.9.283 has released, but this patch is not merged. It's exactly a bug.

Quoted 122 lines · Cheng Chao

the bug has been introduced by the patch:
   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/drivers/staging/android/ion/ion_system_heap.c?h=v4.9.282&id=e7f63771b60e7802c5a9b437c5ab1a8e33a0bb35
Quoted 117 lines · Cheng Chao
for longterm v4.4.283, the code has checked if (!page)
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/staging/android/ion/ion_system_heap.c?h=v4.4.283
static struct page *alloc_buffer_page(struct ion_system_heap *heap,
struct ion_buffer *buffer,
unsigned long order)
{
...
if (!cached) {
page = ion_page_pool_alloc(pool);
} else {
...
page = alloc_pages(gfp_flags | __GFP_COMP, order);
if (!page) <---
return NULL; <---
ion_pages_sync_for_device(NULL, page, PAGE_SIZE << order,
...
}
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
for longterm v4.14.246, has no ion_pages_sync_for_device after ion_page_pool_alloc
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/staging/android/ion/ion_system_heap.c?h=v4.14.246
static struct page *alloc_buffer_page(struct ion_system_heap *heap,
struct ion_buffer *buffer,
unsigned long order)
{
...
if (!cached)
pool = heap->uncached_pools[order_to_index(order)];
else
pool = heap->cached_pools[order_to_index(order)];
page = ion_page_pool_alloc(pool);
return page;
}
----------------------------------------------------------------------------------------------------------------------------------------------------------
after longterm v4.19.206(include),
static struct page *alloc_buffer_page(struct ion_system_heap *heap,
struct ion_buffer *buffer,
unsigned long order)
{
struct ion_page_pool *pool = heap->pools[order_to_index(order)];
return ion_page_pool_alloc(pool);
}
Quoted 61 lines · Greg KH
Quoted 50 lines · Cheng Chao
kernel panic is here:
Unable to handle kernel paging request at virtual address b0380000
pgd = d9d94000
[b0380000] *pgd=00000000
Internal error: Oops: 2805 [#1] PREEMPT SMP ARM
...
task: daa2dd00 task.stack: da194000
PC is at v7_dma_clean_range+0x1c/0x34
LR is at arm_dma_sync_single_for_device+0x44/0x58
pc : [<c011aa0c>]    lr : [<c011645c>]    psr: 200f0013
sp : da195da0 ip : dc1f9000 fp : c1043dc4
r10: 00000000 r9 : c16f1f58 r8 : 00000001
r7 : c1621f94 r6 : c0116418 r5 : 00000000 r4 : c011aa58
r3 : 0000003f r2 : 00000040 r1 : b0480000 r0 : b0380000
Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5383d Table: 19d9406a DAC: 00000051
...
[<c011aa0c>] (v7_dma_clean_range) from [<c011645c>] (arm_dma_sync_single_for_device+0x44/0x58) [<c011645c>] (arm_dma_sync_single_for_device) from [<c0117088>] (arm_dma_sync_sg_for_device+0x50/0x7c) [<c0117088>] (arm_dma_sync_sg_for_device) from [<c0c033c4>] (ion_pages_sync_for_device+0xb0/0xec) [<c0c033c4>] (ion_pages_sync_for_device) from [<c0c054ac>] (ion_system_heap_allocate+0x2a0/0x2e0) [<c0c054ac>] (ion_system_heap_allocate) from [<c0c02c78>] (ion_alloc+0x12c/0x494) [<c0c02c78>] (ion_alloc) from [<c0c03eac>] (ion_ioctl+0x510/0x63c)
[<c0c03eac>] (ion_ioctl) from [<c027c4b0>] (do_vfs_ioctl+0xa8/0x9b4)
[<c027c4b0>] (do_vfs_ioctl) from [<c027ce28>] (SyS_ioctl+0x6c/0x7c)
[<c027ce28>] (SyS_ioctl) from [<c0108a40>] (ret_fast_syscall+0x0/0x48)
Code: e3a02004 e1a02312 e2423001 e1c00003 (ee070f3a)
---[ end trace 89278304932c0e87 ]---
Kernel panic - not syncing: Fatal exception
Signed-off-by Cheng Chao <[email protected]>
---
 drivers/staging/android/ion/ion_system_heap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/staging/android/ion/ion_system_heap.c +1 -2
index 22c481f2ae4f..2a35b99cf628 100644
@@ -75,7 +75,7 @@ static struct page *alloc_buffer_page(struct ion_system_heap *heap,
 
      page = ion_page_pool_alloc(pool);
 
-     if (cached)
+     if (page && cached)
              ion_pages_sync_for_device(NULL, page, PAGE_SIZE << order,
                                        DMA_BIDIRECTIONAL);
      return page;
--
Quoted 2 lines
2.26.3
Why is this just a 4.9 patch? Ion didn't get removed until 5.11, so wouldn't this be an issue for anything 5.10 and older?
thanks,
greg k-h

Greg KH

maintainer

2021-09-23 08:05 UTC #5 lore raw

Quoted 2 lines · Cheng Chao

I notice that v4.9.283 has released, but this patch is not merged. It's exactly a bug.

Can you please resend this and include all of the information in this thread in the changelog comment explaining why this is only needed for this one branch? Trying to piece it all together on my own doesn't work well :)

thanks,

greg k-h

Cheng Chao

author

2021-09-23 14:18 UTC #7 lore raw

PATCH 1/1 staging: android: ion: fix page is NULL

In reply to Cheng Chao

Fixes commit e7f63771b60e ("ION: Sys_heap: Add cached pool to spead up cached buffer alloc")

the commit e7f63771b60e introduced the bug which didn't test page which maybe NULL. and previous logic was right.

the e7f63771b60e has been merged in v4.8-rc3, only longterm 4.9.x has this bug, and other longterm/stable version have not.

kernel panic is here when page is NULL:

Unable to handle kernel paging request at virtual address b0380000
pgd = d9d94000
[b0380000] *pgd=00000000
Internal error: Oops: 2805 [#1] PREEMPT SMP ARM

...
task: daa2dd00 task.stack: da194000
PC is at v7_dma_clean_range+0x1c/0x34
LR is at arm_dma_sync_single_for_device+0x44/0x58

pc : [<c011aa0c>]    lr : [<c011645c>]    psr: 200f0013

Code: e3a02004 e1a02312 e2423001 e1c00003 (ee070f3a)
---[ end trace 89278304932c0e87 ]---
Kernel panic - not syncing: Fatal exception

Signed-off-by Cheng Chao <[email protected]>

---
 drivers/staging/android/ion/ion_system_heap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

drivers/staging/android/ion/ion_system_heap.c +1 -1

index 22c481f2ae4f..2a35b99cf628 100644
@@ -75,7 +75,7 @@ static struct page *alloc_buffer_page(struct ion_system_heap *heap,
 
 	page = ion_page_pool_alloc(pool);
 
-	if (cached)
+	if (page && cached)
 		ion_pages_sync_for_device(NULL, page, PAGE_SIZE << order,
 					  DMA_BIDIRECTIONAL);
 	return page;

Signature · 1 line

2.26.3

Cheng Chao

author

2021-09-23 14:21 UTC #6 lore raw

PATCH 1/1 staging: android: ion: fix page is NULL

In reply to Cheng Chao

Fixes commit e7f63771b60e ("ION: Sys_heap: Add cached pool to spead up cached buffer alloc")

the commit e7f63771b60e introduced the bug which didn't test page which maybe NULL. and previous logic was right.

the e7f63771b60e has been merged in v4.8-rc3, only longterm 4.9.x has this bug, and other longterm/stable version have not.

kernel panic is here when page is NULL:

Unable to handle kernel paging request at virtual address b0380000
pgd = d9d94000
[b0380000] *pgd=00000000
Internal error: Oops: 2805 [#1] PREEMPT SMP ARM

...
task: daa2dd00 task.stack: da194000
PC is at v7_dma_clean_range+0x1c/0x34
LR is at arm_dma_sync_single_for_device+0x44/0x58

pc : [<c011aa0c>]    lr : [<c011645c>]    psr: 200f0013

Code: e3a02004 e1a02312 e2423001 e1c00003 (ee070f3a)
---[ end trace 89278304932c0e87 ]---
Kernel panic - not syncing: Fatal exception

Signed-off-by Cheng Chao <[email protected]>

---
 drivers/staging/android/ion/ion_system_heap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

drivers/staging/android/ion/ion_system_heap.c +1 -1

index 22c481f2ae4f..2a35b99cf628 100644
@@ -75,7 +75,7 @@ static struct page *alloc_buffer_page(struct ion_system_heap *heap,
 
 	page = ion_page_pool_alloc(pool);
 
-	if (cached)
+	if (page && cached)
 		ion_pages_sync_for_device(NULL, page, PAGE_SIZE << order,
 					  DMA_BIDIRECTIONAL);
 	return page;

Signature · 1 line

2.26.3

Greg KH

maintainer

2021-09-23 14:24 UTC #8 lore raw

In reply to Cheng Chao

Quoted 6 lines · Cheng Chao

Fixes commit e7f63771b60e ("ION: Sys_heap: Add cached pool to spead up cached buffer alloc")
the commit e7f63771b60e introduced the bug which didn't test page which maybe NULL. and previous logic was right.
the e7f63771b60e has been merged in v4.8-rc3, only longterm 4.9.x has this bug, and other longterm/stable version have not.

<snip>

thanks for this, now queued up.

greg k-h