Messages in this thread | | | Subject | Re: [PATCH AUTOSEL 5.2 13/23] drm/i915/userptr: Acquire the page lock around set_page_dirty() | From | Thomas Backlund <> | Date | Thu, 12 Sep 2019 23:51:33 +0300 |
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Den 03-09-2019 kl. 19:24, skrev Sasha Levin: > From: Chris Wilson <chris@chris-wilson.co.uk> > > [ Upstream commit aa56a292ce623734ddd30f52d73f527d1f3529b5 ] > > set_page_dirty says: > > For pages with a mapping this should be done under the page lock > for the benefit of asynchronous memory errors who prefer a > consistent dirty state. This rule can be broken in some special > cases, but should be better not to. > > Under those rules, it is only safe for us to use the plain set_page_dirty > calls for shmemfs/anonymous memory. Userptr may be used with real > mappings and so needs to use the locked version (set_page_dirty_lock). > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203317 > Fixes: 5cc9ed4b9a7a ("drm/i915: Introduce mapping of user pages into video memory (userptr) ioctl") > References: 6dcc693bc57f ("ext4: warn when page is dirtied without buffers") > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> > Cc: stable@vger.kernel.org > Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> > Link: https://patchwork.freedesktop.org/patch/msgid/20190708140327.26825-1-chris@chris-wilson.co.uk > (cherry picked from commit cb6d7c7dc7ff8cace666ddec66334117a6068ce2) > Signed-off-by: Jani Nikula <jani.nikula@intel.com> > Signed-off-by: Sasha Levin <sashal@kernel.org> > --- > drivers/gpu/drm/i915/i915_gem_userptr.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c > index 8079ea3af1039..b1fc15c7f5997 100644 > --- a/drivers/gpu/drm/i915/i915_gem_userptr.c > +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c > @@ -678,7 +678,15 @@ i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj, > > for_each_sgt_page(page, sgt_iter, pages) { > if (obj->mm.dirty) > - set_page_dirty(page); > + /* > + * As this may not be anonymous memory (e.g. shmem) > + * but exist on a real mapping, we have to lock > + * the page in order to dirty it -- holding > + * the page reference is not sufficient to > + * prevent the inode from being truncated. > + * Play safe and take the lock. > + */ > + set_page_dirty_lock(page); > > mark_page_accessed(page); > put_page(page); >
Please drop this one from all 5.2 and 4.19 stable queues
It has now been reverted in Linus tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=505a8ec7e11ae5236c4a154a1e24ef49a8349600
-- Thomas
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