On 6/22/20 5:41 AM, Daniel Vetter wrote:
On Sun, Jun 21, 2020 at 02:03:02AM -0400, Andrey Grodzovsky wrote:
On device removal reroute all CPU mappings to dummy page per drm_file
instance or imported GEM object.
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>
---
drivers/gpu/drm/ttm/ttm_bo_vm.c | 65 ++++++++++++++++++++++++++++++++++++-----
1 file changed, 57 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 389128b..2f8bf5e 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -35,6 +35,8 @@
#include <drm/ttm/ttm_bo_driver.h>
#include <drm/ttm/ttm_placement.h>
#include <drm/drm_vma_manager.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_file.h>
#include <linux/mm.h>
#include <linux/pfn_t.h>
#include <linux/rbtree.h>
@@ -328,19 +330,66 @@ vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
Hm I think diff and code flow look a bit bad now. What about renaming the
current function to __ttm_bo_vm_fault and then having something like the
below:
ttm_bo_vm_fault(args) {
if (drm_dev_enter()) {
__ttm_bo_vm_fault(args);
drm_dev_exit();
} else {
drm_gem_insert_dummy_pfn();
}
}
I think drm_gem_insert_dummy_pfn(); should be portable across drivers, so
another nice point to try to unifiy drivers as much as possible.
-Daniel
pgprot_t prot;
struct ttm_buffer_object *bo = vma->vm_private_data;
vm_fault_t ret;
+ int idx;
+ struct drm_device *ddev = bo->base.dev;
- ret = ttm_bo_vm_reserve(bo, vmf);
- if (ret)
- return ret;
+ if (drm_dev_enter(ddev, &idx)) {
+ ret = ttm_bo_vm_reserve(bo, vmf);
+ if (ret)
+ goto exit;
+
+ prot = vma->vm_page_prot;
- prot = vma->vm_page_prot;
- ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT);
- if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
+ ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT);
+ if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
+ goto exit;
+
+ dma_resv_unlock(bo->base.resv);
+
+exit:
+ drm_dev_exit(idx);
return ret;
+ } else {
- dma_resv_unlock(bo->base.resv);
+ struct drm_file *file = NULL;
+ struct page *dummy_page = NULL;
+ int handle;
- return ret;
+ /* We are faulting on imported BO from dma_buf */
+ if (bo->base.dma_buf && bo->base.import_attach) {
+ dummy_page = bo->base.dummy_page;
+ /* We are faulting on non imported BO, find drm_file owning the BO*/
Uh, we can't fish that out of the vma->vm_file pointer somehow? Or is that
one all wrong? Doing this kind of list walk looks pretty horrible.
If the vma doesn't have the right pointer I guess next option is that we
store the drm_file page in gem_bo->dummy_page, and replace it on first
export. But that's going to be tricky to track ...
+ } else {
+ struct drm_gem_object *gobj;
+
+ mutex_lock(&ddev->filelist_mutex);
+ list_for_each_entry(file, &ddev->filelist, lhead) {
+ spin_lock(&file->table_lock);
+ idr_for_each_entry(&file->object_idr, gobj, handle) {
+ if (gobj == &bo->base) {
+ dummy_page = file->dummy_page;
+ break;
+ }
+ }
+ spin_unlock(&file->table_lock);
+ }
+ mutex_unlock(&ddev->filelist_mutex);
+ }
+
+ if (dummy_page) {
+ /*
+ * Let do_fault complete the PTE install e.t.c using vmf->page
+ *
+ * TODO - should i call free_page somewhere ?
Nah, instead don't call get_page. The page will be around as long as
there's a reference for the drm_file or gem_bo, which is longer than any
mmap. Otherwise yes this would like really badly.
So actually that was my thinking in the first place and I indeed avoided taking
reference and this ended up
with multiple BUG_ONs as seen bellow where refcount:-63 mapcount:-48 for a page
are deep into negative
values... Those warnings were gone once i added get_page(dummy) which in my
opinion implies that there
is a page reference per each PTE and that when there is unmapping of the process
address
space and PTEs are deleted there is also put_page somewhere in mm core and the
get_page per mapping
keeps it balanced.
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762929] BUG: Bad page map in
process glxgear:disk$0 pte:8000000132284867 pmd:15aaec067
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762931] page:ffffe63384c8a100
refcount:-63 mapcount:-48 mapping:0000000000000000 index:0x0
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762932] flags:
0x17fff8000000008(dirty)
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762933] raw: 017fff8000000008
dead000000000100 dead000000000122 0000000000000000
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762934] raw: 0000000000000000
0000000000000000 ffffffc1ffffffcf 0000000000000000
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762935] page dumped because: bad pte
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762937] addr:00007fe086263000
vm_flags:1c0440fb anon_vma:0000000000000000 mapping:ffff9b5cd42db268 index:1008b3
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762981] file:renderD129
fault:ttm_bo_vm_fault [ttm] mmap:amdgpu_mmap [amdgpu] readpage:0x0
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762984] CPU: 5 PID: 2619 Comm:
glxgear:disk$0 Tainted: G B OE 5.6.0-dev+ #51
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762985] Hardware name: System
manufacturer System Product Name/RAMPAGE IV FORMULA, BIOS 4804 12/30/2013
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762985] Call Trace:
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762988] dump_stack+0x68/0x9b
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762990] print_bad_pte+0x19f/0x270
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762992] ? lock_page_memcg+0x5/0xf0
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.762995] unmap_page_range+0x777/0xbe0
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763000] unmap_vmas+0xcc/0x160
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763004] exit_mmap+0xb5/0x1b0
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763009] mmput+0x65/0x140
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763010] do_exit+0x362/0xc40
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763013] do_group_exit+0x47/0xb0
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763016] get_signal+0x18b/0xc30
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763019] do_signal+0x36/0x6a0
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763021] ?
__set_task_comm+0x62/0x120
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763024] ?
__x64_sys_futex+0x88/0x180
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763028]
exit_to_usermode_loop+0x6f/0xc0
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763030] do_syscall_64+0x149/0x1c0
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763032]
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763034] RIP: 0033:0x7fe091bd9360
Jun 20 01:36:43 ubuntu-1604-test kernel: [ 98.763037] Code: Bad RIP value.
Andrey
+ */
+ get_page(dummy_page);
+ vmf->page = dummy_page;
+ return 0;
+ } else {
+ return VM_FAULT_SIGSEGV;
Hm that would be a kernel bug, wouldn't it? WARN_ON() required here imo.
-Daniel
+ }
+ }
}
EXPORT_SYMBOL(ttm_bo_vm_fault);
--
2.7.4
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