Hi
Am 12.03.26 um 18:46 schrieb Biju Das:
Hi Tommaso,
-----Original Message-----
From: Tommaso Merciai <[email protected]>
Sent: 12 March 2026 17:37
Subject: Re: [PATCH v4 5/6] drm/gem-shmem: Track folio accessed/dirty status in
mmap
Hi Thomas,
Thanks for your patch.
I'm working on DSI support for RZ/G3E from this morning rebasing on top of
next-20260311 I'm seeing
that weston hang on my side:
Reverting this patch fix the issue.
(git revert 28e3918179aa)
Just a guess, but maybe vm_file is NULL. The attached patch should
handle this. Could either of you please test?
Best regards
Thomas
I'm wondering if anyone encountered this issue?
Thanks in advance.
I am also seeing same issue on RZ/G3L with weston.
Cheers,
Biju
Kind Regards,
Tommaso
On Fri, Feb 27, 2026 at 12:42:10PM +0100, Thomas Zimmermann wrote:
Invoke folio_mark_accessed() in mmap page faults to add the folio to
the memory manager's LRU list. Userspace invokes mmap to get the
memory for software rendering. Compositors do the same when creating
the final on-screen image, so keeping the pages in LRU makes sense.
Avoids paging out graphics buffers when under memory pressure.
In pfn_mkwrite, further invoke the folio_mark_dirty() to add the folio
for writeback should the underlying file be paged out from system memory.
This rarely happens in practice, yet it would corrupt the buffer content.
This has little effect on a system's hardware-accelerated rendering,
which only mmaps for an initial setup of textures, meshes, shaders, etc.
v4:
- test for VM_FAULT_NOPAGE before marking folio as accessed (Boris)
- test page-array bounds in mkwrite handler (Boris)
v3:
- rewrite for VM_PFNMAP
v2:
- adapt to changes in drm_gem_shmem_try_mmap_pmd()
Signed-off-by: Thomas Zimmermann <[email protected]>
Reviewed-by: Boris Brezillon <[email protected]>
---
drivers/gpu/drm/drm_gem_shmem_helper.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c
b/drivers/gpu/drm/drm_gem_shmem_helper.c
index cefa50eaf7a4..1ab2bbd3860c 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -598,6 +598,9 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
if (ret != VM_FAULT_NOPAGE)
ret = vmf_insert_pfn(vma, vmf->address, pfn);
+ if (ret == VM_FAULT_NOPAGE)
+ folio_mark_accessed(folio);
+
out:
dma_resv_unlock(obj->resv);
@@ -638,10 +641,29 @@ static void drm_gem_shmem_vm_close(struct vm_area_struct
*vma)
drm_gem_vm_close(vma);
}
+static vm_fault_t drm_gem_shmem_pfn_mkwrite(struct vm_fault *vmf) {
+ struct vm_area_struct *vma = vmf->vma;
+ struct drm_gem_object *obj = vma->vm_private_data;
+ struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+ loff_t num_pages = obj->size >> PAGE_SHIFT;
+ pgoff_t page_offset = vmf->pgoff - vma->vm_pgoff; /* page offset
+within VMA */
+
+ if (drm_WARN_ON(obj->dev, !shmem->pages || page_offset >= num_pages))
+ return VM_FAULT_SIGBUS;
+
+ file_update_time(vma->vm_file);
+
+ folio_mark_dirty(page_folio(shmem->pages[page_offset]));
+
+ return 0;
+}
+
const struct vm_operations_struct drm_gem_shmem_vm_ops = {
.fault = drm_gem_shmem_fault,
.open = drm_gem_shmem_vm_open,
.close = drm_gem_shmem_vm_close,
+ .pfn_mkwrite = drm_gem_shmem_pfn_mkwrite,
};
EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
--
2.52.0
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)
From e64346c6b3d946e4424066d888cb41fe60eb9d88 Mon Sep 17 00:00:00 2001
From: Thomas Zimmermann <[email protected]>
Date: Fri, 13 Mar 2026 09:29:26 +0100
Subject: [PATCH] test for vm_file before updating file access time
---
drivers/gpu/drm/drm_gem_shmem_helper.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 4500deef4127..7fad72cc01dc 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -656,7 +656,8 @@ static vm_fault_t drm_gem_shmem_pfn_mkwrite(struct vm_fault *vmf)
if (drm_WARN_ON(obj->dev, !shmem->pages || page_offset >= num_pages))
return VM_FAULT_SIGBUS;
- file_update_time(vma->vm_file);
+ if (vma->vm_file)
+ file_update_time(vma->vm_file);
folio_mark_dirty(page_folio(shmem->pages[page_offset]));
--
2.53.0
