[PATCH] drm/ttm: fix deref of bo->ttm without holding the lock v2

[Christian König]

I take that as an reviewed-by :)

Thanks,
Christian.

Am 07.06.21 um 16:14 schrieb Pan, Xinhui:
>
> [AMD Official Use Only]
>
>
> Looks good to me.
> ------------------------------------------------------------------------
> *From:* Christian König <ckoenig.leichtzumerken at gmail.com>
> *Sent:* Monday, June 7, 2021 8:52:21 PM
> *To:* dri-devel at lists.freedesktop.org 
> <dri-devel at lists.freedesktop.org>; Pan, Xinhui <Xinhui.Pan at amd.com>; 
> Das, Nirmoy <Nirmoy.Das at amd.com>; Huang, Ray <Ray.Huang at amd.com>
> *Cc:* Thomas Hellström <thomas.hellstrom at linux.intel.com>
> *Subject:* Re: [PATCH] drm/ttm: fix deref of bo->ttm without holding 
> the lock v2
>
>
> Am 28.05.21 um 15:06 schrieb Thomas Hellström:
> >
> > On 5/28/21 3:00 PM, Christian König wrote:
> >> We need to grab the resv lock first before doing that check.
> >>
> >> v2 (chk): simplify the change for -fixes
> >>
> >> Signed-off-by: Christian König <christian.koenig at amd.com>
> >> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> >
> > Hmm, OK, but this doesn't fix the swapped-bo-not-on-lru and
> > unpopulating from swap_notify issues. Are you planning a follow up
> > patch for those?
>
> As discussed in a separate thread this needs to be applied as needed
> when the DG1 branch is merged.
>
> Xinhui, Nirmoy, Rui can anybody give be an rb/ab so that I can push this?
>
> Thanks,
> Christian.
>
> >
> > Thanks,
> >
> > Thomas
> >
> >> ---
> >>   drivers/gpu/drm/ttm/ttm_bo.c     | 5 ++++-
> >>   drivers/gpu/drm/ttm/ttm_device.c | 8 +-------
> >>   2 files changed, 5 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c 
> b/drivers/gpu/drm/ttm/ttm_bo.c
> >> index cfd0b9292397..ebcffe794adb 100644
> >> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> >> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> >> @@ -1172,7 +1172,10 @@ int ttm_bo_swapout(struct ttm_buffer_object
> >> *bo, struct ttm_operation_ctx *ctx,
> >>       if (!ttm_bo_evict_swapout_allowable(bo, ctx, &locked, NULL))
> >>           return -EBUSY;
> >>   -    if (!ttm_bo_get_unless_zero(bo)) {
> >> +    if (!bo->ttm || !ttm_tt_is_populated(bo->ttm) ||
> >> +        bo->ttm->page_flags & TTM_PAGE_FLAG_SG ||
> >> +        bo->ttm->page_flags & TTM_PAGE_FLAG_SWAPPED ||
> >> +        !ttm_bo_get_unless_zero(bo)) {
> >>           if (locked)
> >> dma_resv_unlock(bo->base.resv);
> >>           return -EBUSY;
> >> diff --git a/drivers/gpu/drm/ttm/ttm_device.c
> >> b/drivers/gpu/drm/ttm/ttm_device.c
> >> index a1dcf7d55c90..3d9c62b93e29 100644
> >> --- a/drivers/gpu/drm/ttm/ttm_device.c
> >> +++ b/drivers/gpu/drm/ttm/ttm_device.c
> >> @@ -143,14 +143,8 @@ int ttm_device_swapout(struct ttm_device *bdev,
> >> struct ttm_operation_ctx *ctx,
> >>             for (j = 0; j < TTM_MAX_BO_PRIORITY; ++j) {
> >>               list_for_each_entry(bo, &man->lru[j], lru) {
> >> -                uint32_t num_pages;
> >> +                uint32_t num_pages = PFN_UP(bo->base.size);
> >>   -                if (!bo->ttm || !ttm_tt_is_populated(bo->ttm) ||
> >> -                    bo->ttm->page_flags & TTM_PAGE_FLAG_SG ||
> >> -                    bo->ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)
> >> -                    continue;
> >> -
> >> -                num_pages = bo->ttm->num_pages;
> >>                   ret = ttm_bo_swapout(bo, ctx, gfp_flags);
> >>                   /* ttm_bo_swapout has dropped the lru_lock */
> >>                   if (!ret)
>

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