linux-kernel - Re: [PATCH v16 15/20] drm/shmem-helper: Add memory shrinker

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Message-ID: <ac995ee3-9819-9b10-a7ae-642720828b32@collabora.com>
Date:   Tue, 12 Sep 2023 02:44:55 +0300
From:   Dmitry Osipenko <dmitry.osipenko@...labora.com>
To:     Dan Carpenter <dan.carpenter@...aro.org>,
        oe-kbuild@...ts.linux.dev, 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 <bbrezillon@...nel.org>,
        Emma Anholt <emma@...olt.net>, Melissa Wen <mwen@...lia.com>
Cc:     lkp@...el.com, oe-kbuild-all@...ts.linux.dev, kernel@...labora.com,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v16 15/20] drm/shmem-helper: Add memory shrinker

On 9/7/23 13:03, Dan Carpenter wrote:
> 2c607edf57db6a Dmitry Osipenko 2023-09-03 @724  	if (page_offset >= num_pages || (!shmem->pages && !shmem->evicted)) {
>                                                                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Should this be || instead of &&?  (The other thing that people do is
> add "!shmem->evicted" for readability even though it doesn't need to be
> checked.  So maybe that's the issue, but the checker assumes it needs to
> be checked).
> 
> d611b4a0907cec Neil Roberts    2021-02-23  725  		ret = VM_FAULT_SIGBUS;
> d611b4a0907cec Neil Roberts    2021-02-23  726  	} else {
> 2c607edf57db6a Dmitry Osipenko 2023-09-03  727  		err = drm_gem_shmem_swapin_locked(shmem);
> 
> Or maybe it's because the kbuild bot can't use the cross function db
> and shmem->pages is assigned here?

Should be a function db problem. The shmem->pages won't be NULL if
drm_gem_shmem_swapin_locked() succeeds.

-- 
Best regards,
Dmitry