linux-kernel - [PATCH v15 12/23] drm/shmem-helper: Add and use pages_pin

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230827175449.1766701-13-dmitry.osipenko@collabora.com>
Date:   Sun, 27 Aug 2023 20:54:38 +0300
From:   Dmitry Osipenko <dmitry.osipenko@...labora.com>
To:     David Airlie <airlied@...il.com>,
        Gerd Hoffmann <kraxel@...hat.com>,
        Gurchetan Singh <gurchetansingh@...omium.org>,
        Chia-I Wu <olvaffe@...il.com>, Daniel Vetter <daniel@...ll.ch>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Christian König <christian.koenig@....com>,
        Qiang Yu <yuq825@...il.com>,
        Steven Price <steven.price@....com>,
        Boris Brezillon <boris.brezillon@...labora.com>,
        Emma Anholt <emma@...olt.net>, Melissa Wen <mwen@...lia.com>,
        Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Boqun Feng <boqun.feng@...il.com>,
        Mark Rutland <mark.rutland@....com>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        kernel@...labora.com, virtualization@...ts.linux-foundation.org,
        intel-gfx@...ts.freedesktop.org
Subject: [PATCH v15 12/23] drm/shmem-helper: Add and use pages_pin_count

Add separate pages_pin_count for tracking of whether drm-shmem pages are
moveable or not. With the addition of memory shrinker support to drm-shmem,
the pages_use_count will no longer determine whether pages are hard-pinned
in memory, but whether pages exit and are soft-pinned (and could be swapped
out). The pages_pin_count > 1 will hard-pin pages in memory.

Suggested-by: Boris Brezillon <boris.brezillon@...labora.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
---
 drivers/gpu/drm/drm_gem_shmem_helper.c | 22 +++++++++++++++++-----
 include/drm/drm_gem_shmem_helper.h     | 10 ++++++++++
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index d545d3d227d7..1a7e5c332fd8 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -234,14 +234,22 @@ static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
 
 	dma_resv_assert_held(shmem->base.resv);
 
+	if (kref_get_unless_zero(&shmem->pages_pin_count))
+		return 0;
+
 	ret = drm_gem_shmem_get_pages_locked(shmem);
+	if (!ret)
+		kref_init(&shmem->pages_pin_count);
 
 	return ret;
 }
 
-static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem)
+static void drm_gem_shmem_kref_unpin_pages(struct kref *kref)
 {
-	dma_resv_assert_held(shmem->base.resv);
+	struct drm_gem_shmem_object *shmem;
+
+	shmem = container_of(kref, struct drm_gem_shmem_object,
+			     pages_pin_count);
 
 	drm_gem_shmem_put_pages_locked(shmem);
 }
@@ -263,6 +271,9 @@ int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem)
 
 	drm_WARN_ON(obj->dev, obj->import_attach);
 
+	if (kref_get_unless_zero(&shmem->pages_pin_count))
+		return 0;
+
 	ret = dma_resv_lock_interruptible(shmem->base.resv, NULL);
 	if (ret)
 		return ret;
@@ -286,9 +297,10 @@ void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem)
 
 	drm_WARN_ON(obj->dev, obj->import_attach);
 
-	dma_resv_lock(shmem->base.resv, NULL);
-	drm_gem_shmem_unpin_locked(shmem);
-	dma_resv_unlock(shmem->base.resv);
+	if (kref_put_dma_resv(&shmem->pages_pin_count,
+			      drm_gem_shmem_kref_unpin_pages,
+			      obj->resv, NULL))
+		dma_resv_unlock(obj->resv);
 }
 EXPORT_SYMBOL_GPL(drm_gem_shmem_unpin);
 
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index ec2d8b24e3cf..afb7cd671e2a 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -39,6 +39,16 @@ struct drm_gem_shmem_object {
 	 */
 	unsigned int pages_use_count;
 
+	/**
+	 * @pages_pin_count:
+	 *
+	 * Reference count on the pinned pages table.
+	 * The pages allowed to be evicted and purged by memory
+	 * shrinker only when the count is zero, otherwise pages
+	 * are hard-pinned in memory.
+	 */
+	struct kref pages_pin_count;
+
 	/**
 	 * @madv: State for madvise
 	 *
-- 
2.41.0