linux-kernel - Re: [PATCH] shmem: fix pageflags after swapping DMA32 object

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Date:   Mon, 7 Nov 2016 14:29:00 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Hugh Dickins <hughd@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        intel-gfx@...ts.freedesktop.org
Subject: Re: [PATCH] shmem: fix pageflags after swapping DMA32 object

On Sun, Nov 06, 2016 at 08:08:29PM -0800, Hugh Dickins wrote:
> If shmem_alloc_page() does not set PageLocked and PageSwapBacked, then
> shmem_replace_page() needs to do so for itself.  Without this, it puts
> newpage on the wrong lru, re-unlocks the unlocked newpage, and system
> descends into "Bad page" reports and freeze; or if CONFIG_DEBUG_VM=y,
> it hits an earlier VM_BUG_ON_PAGE(!PageLocked), depending on config.
> 
> But shmem_replace_page() is not a common path: it's only called when
> swapin (or swapoff) finds the page was already read into an unsuitable
> zone: usually all zones are suitable, but gem objects for a few drm
> devices (gma500, omapdrm, crestline, broadwater) require zone DMA32
> if there's more than 4GB of ram.
> 
> Fixes: 800d8c63b2e9 ("shmem: add huge pages support")
> Cc: stable@...r.kernel.org # v4.8
> Signed-off-by: Hugh Dickins <hughd@...gle.com>

Sorry for that.

Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

-- 
 Kirill A. Shutemov