So I got a report that "the backport of "drm/ttm: Fix ttm_bo_swapout() infinite LRU walk on swapout failure" to yesterday's 6.18 missed "drm/ttm: fix swapped-out resources never leaving their bulk_move range",
So can we make sure this patch is in the stable branches the other one went into? Thanks, Dave. On Wed, 23 Sept 2026 at 20:51, Greg KH <[email protected]> wrote: > > On Wed, Sep 23, 2026 at 09:53:54AM +0200, Christian König wrote: > > Hi Greg, > > > > On 9/23/26 09:41, Greg KH wrote: > > > On Tue, Sep 22, 2026 at 06:33:34PM +0300, Vadim Nikitushkin wrote: > > >> commit 3db7d7d583419f7b1f2e141e36418802dbb25cf8 upstream. > > >> > > >> 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: [email protected] # v7.1+ > > >> Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/5387 > > >> Link: > > >> https://lore.kernel.org/dri-devel/cahyinpa6avacjoloje-qz1gyyx-9p0tn4nup8d_esl+ujee...@mail.gmail.com/ > > >> Signed-off-by: Vadim Nikitushkin <[email protected]> > > >> Reviewed-by: Thomas Hellström <[email protected]> > > >> Reviewed-by: Christian König <[email protected]> > > >> Signed-off-by: Christian König <[email protected]> > > >> Link: https://lore.kernel.org/r/[email protected] > > >> [ Squashed with commit fcfe64715b425262af1b36f498f9197f3537ceed > > > > > > Do not squash, send a patch series instead please. > > > > in this particular case that squashing is the correct approach. > > > > AMDs mail servers mangled the initial patch so badly that I had trouble > > applying it and ended up pushing a broken patch upstream. The squash is > > basically fixing that up. > > Ok, I'll take this then, thanks for the response. > > greg k-h
