On 15/03/22 2:35 pm, Paul Menzel wrote: > Dear Arunpravin, > > > Am 15.03.22 um 10:01 schrieb Arunpravin: > >> On 15/03/22 1:49 pm, Paul Menzel wrote: > >>> Am 14.03.22 um 20:40 schrieb Arunpravin: >>>> handle a situation in the condition order-- == min_order, >>>> when order = 0, leading to order = -1, it now won't exit >>>> the loop. To avoid this problem, added a order check in >>>> the same condition, (i.e) when order is 0, we return >>>> -ENOSPC >>>> >>>> Signed-off-by: Arunpravin <Arunpravin.PaneerSelvam@xxxxxxx> >>> >>> Please use your full name. >> okay > > You might also configure that in your email program. yes > >>>> --- >>>> drivers/gpu/drm/drm_buddy.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c >>>> index 72f52f293249..5ab66aaf2bbd 100644 >>>> --- a/drivers/gpu/drm/drm_buddy.c >>>> +++ b/drivers/gpu/drm/drm_buddy.c >>> >>> In what tree is that file? >>> >> drm-tip - https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcgit.freedesktop.org%2Fdrm-tip%2Ftree%2F&data=04%7C01%7CArunpravin.PaneerSelvam%40amd.com%7Cc456573102c04191cf9708da0662f798%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637829319396954551%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=5Bspe5QGjQ0KHfVI8%2F%2BXqxR45q6tOL4FE2fVD3uwL%2FM%3D&reserved=0 >> drm-misc-next - https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcgit.freedesktop.org%2Fdrm%2Fdrm-misc%2Ftree%2F&data=04%7C01%7CArunpravin.PaneerSelvam%40amd.com%7Cc456573102c04191cf9708da0662f798%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637829319396954551%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=g2S14TfsHF5ORo9jTZ3uA0l1BH8mnAxk2OWYJeF5i8k%3D&reserved=0 >> >>>> @@ -685,7 +685,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm, >>>> if (!IS_ERR(block)) >>>> break; >>>> >>>> - if (order-- == min_order) { >>>> + if (!order || order-- == min_order) { >>>> err = -ENOSPC; >>>> goto err_free; >>>> } > > Thank you for the hint. So the whole function is: > > do { > order = min(order, (unsigned int)fls(pages) - 1); > BUG_ON(order > mm->max_order); > BUG_ON(order < min_order); > > do { > if (flags & DRM_BUDDY_RANGE_ALLOCATION) > /* Allocate traversing within the range */ > block = alloc_range_bias(mm, start, end, order); > else > /* Allocate from freelist */ > block = alloc_from_freelist(mm, order, flags); > > if (!IS_ERR(block)) > break; > > if (order-- == min_order) { > err = -ENOSPC; > goto err_free; > } > } while (1); > > mark_allocated(block); > mm->avail -= drm_buddy_block_size(mm, block); > kmemleak_update_trace(block); > list_add_tail(&block->link, &allocated); > > pages -= BIT(order); > > if (!pages) > break; > } while (1); > > Was the BUG_ON triggered for your case? > > BUG_ON(order < min_order); no, this BUG_ON is not triggered for this bug > > Please give more details. there is a chance when there is no space to allocate, order value decrements and reaches to 0 at one point, here we should exit the loop, otherwise, further order value decrements to -1 and do..while loop doesn't exit. Hence added a check to exit the loop if order value becomes 0. Thanks, Arun > > > Kind regards, > > Paul >
