linux-ext4 - [PATCH v1 05/12] drm/amdkfd: ref count init for device pages

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Date:   Tue, 12 Oct 2021 12:12:40 -0500
From:   Alex Sierra <alex.sierra@....com>
To:     <akpm@...ux-foundation.org>, <Felix.Kuehling@....com>,
        <linux-mm@...ck.org>, <rcampbell@...dia.com>,
        <linux-ext4@...r.kernel.org>, <linux-xfs@...r.kernel.org>
CC:     <amd-gfx@...ts.freedesktop.org>, <dri-devel@...ts.freedesktop.org>,
        <hch@....de>, <jgg@...dia.com>, <jglisse@...hat.com>,
        <apopple@...dia.com>
Subject: [PATCH v1 05/12] drm/amdkfd: ref count init for device pages

Ref counter from device pages is init to zero during memmap init zone.
The first time a new device page is allocated to migrate data into it,
its ref counter needs to be initialized to one.

Signed-off-by: Alex Sierra <alex.sierra@....com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
index dab290a4d19d..ffad39ffa8c6 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
@@ -220,7 +220,8 @@ svm_migrate_get_vram_page(struct svm_range *prange, unsigned long pfn)
 	page = pfn_to_page(pfn);
 	svm_range_bo_ref(prange->svm_bo);
 	page->zone_device_data = prange->svm_bo;
-	get_page(page);
+	VM_BUG_ON_PAGE(page_ref_count(page), page);
+	init_page_count(page);
 	lock_page(page);
 }
 
-- 
2.32.0