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| author | Vadim Nikitushkin <bub4z0r@gmail.com> | 2026-09-09 23:50:28 +0300 |
|---|---|---|
| committer | Christian König <christian.koenig@amd.com> | 2026-09-10 15:40:57 +0200 |
| commit | 3db7d7d583419f7b1f2e141e36418802dbb25cf8 (patch) | |
| tree | 98494b2795a4e226818ee661554d23dff0003189 | |
| parent | 4600b4d1a9ee730d03ddac5ce409cd2730ce8c0c (diff) | |
| download | linux-next-3db7d7d583419f7b1f2e141e36418802dbb25cf8.tar.gz linux-next-3db7d7d583419f7b1f2e141e36418802dbb25cf8.zip | |
drm/ttm: fix swapped-out resources never leaving their bulk_move range
ttm_tt_swapout() returns the number of pages swapped out on success and
a negative error code on failure; for a populated ttm it never returns
zero. Commit b2ed01e7ad3d ("drm/ttm: Fix ttm_bo_swapout() infinite LRU
walk on swapout failure") moved the bulk_move bookkeeping in
ttm_bo_swapout_cb() under "if (!ret)", so the
ttm_resource_del_bulk_move_unevictable() / ttm_resource_move_to_lru_tail()
pair is now skipped on every successful swapout. The equivalent change
for the shrinker in commit 1d59f36e95f7 ("drm/ttm: Fix ttm_bo_shrink()
infinite LRU walk on backup failure") tests "lret > 0", which is what
was intended here as well.
Before b2ed01e7ad3d the resource was taken off the bulk_move before the
swapout; since then a swapped-out resource stays inside its BO's
bulk_move range (and on the manager LRU) although it is unevictable.
When it is later freed or the BO leaves the bulk_move
(ttm_resource_free(), ttm_bo_set_bulk_move() via amdgpu_vm_bo_del()),
ttm_resource_del_bulk_move() skips it because of its
!ttm_resource_unevictable() guard, so a range endpoint in pos->first /
pos->last is left pointing at freed memory. The next
ttm_lru_bulk_move_tail() or ttm_resource_add_bulk_move() on that cursor
is a use-after-free, seen as the resv WARN in ttm_lru_bulk_move_add(),
"list_del corruption" in ttm_resource_move_to_lru_tail() or a NULL
dereference in ttm_resource_manager_next() -- minutes to hours after a
hibernation, or at process exit / reboot following one. Samuel
Ainsworth's analysis of drm/amd issue 5387 (see Link) identified the
dangling cursor; the missing removal at swapout time is the reason it
dangles.
Testing the condition for success restores the removal. On an AMD
Phoenix APU (ASUS UM3406GA, gfx1103) running suspend-then-hibernate on
a 7.0.y stable kernel carrying the backport (Ubuntu 7.0.0-31) the bug
crashed 5 of 18 hibernation cycles; a function profile of one
hibernation showed 336 ttm_tt_swapout() calls and zero
ttm_resource_del_bulk_move_unevictable() calls. With this change the
removal happens for every swapped-out resource and 12 further cycles
were clean.
Fixes: b2ed01e7ad3d ("drm/ttm: Fix ttm_bo_swapout() infinite LRU walk on swapout failure")
Cc: stable@vger.kernel.org # v7.1+
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/5387
Link: https://lore.kernel.org/dri-devel/CAHYiNPa6aVacJoLOje-qZ1GyYx-9p0tN4NuP8D_eSL+UJeevXw@mail.gmail.com/
Signed-off-by: Vadim Nikitushkin <bub4z0r@gmail.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20260909205028.13799-1-bub4z0r@gmail.com
| -rw-r--r-- | drivers/gpu/drm/ttm/ttm_bo.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index ef56c18ded1b..a12af5b38a31 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -532,7 +532,7 @@ static int ttm_bo_alloc_at_place(struct ttm_buffer_object *bo, ret = ttm_resource_try_charge(bo, place, &alloc_state->charge_pool, force_space ? &alloc_state->limit_pool : NULL); - if (ret) { + if (ret > 0) { /* * -EAGAIN means the charge failed, which we treat * like an allocation failure. Therefore, return an |