On Tue, Jun 06, 2023 at 09:24:33AM +0100, Lorenzo Stoakes wrote: > On Tue, Jun 06, 2023 at 10:17:02AM +0200, Uladzislau Rezki wrote: > > On Tue, Jun 06, 2023 at 09:13:24AM +0200, Vlastimil Babka wrote: > > > > > > On 6/5/23 22:11, Lorenzo Stoakes wrote: > > > > In __vmalloc_area_node() we always warn_alloc() when an allocation > > > > performed by vm_area_alloc_pages() fails unless it was due to a pending > > > > fatal signal. > > > > > > > > However, huge page allocations instigated either by vmalloc_huge() or > > > > __vmalloc_node_range() (or a caller that invokes this like kvmalloc() or > > > > kvmalloc_node()) always falls back to order-0 allocations if the huge page > > > > allocation fails. > > > > > > > > This renders the warning useless and noisy, especially as all callers > > > > appear to be aware that this may fallback. This has already resulted in at > > > > least one bug report from a user who was confused by this (see link). > > > > > > > > Therefore, simply update the code to only output this warning for order-0 > > > > pages when no fatal signal is pending. > > > > > > > > Link: https://bugzilla.suse.com/show_bug.cgi?id=1211410 > > > > Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx> > > > > > > I think there are more reports of same thing from the btrfs context, that > > > appear to be a 6.3 regression > > > > > > https://bugzilla.kernel.org/show_bug.cgi?id=217466 > > > Link: https://lore.kernel.org/all/efa04d56-cd7f-6620-bca7-1df89f49bf4b@xxxxxxxxx/ > > > > > I had a look at that report. The btrfs complains due to the > > fact that a high-order page(1 << 9) can not be obtained. In the > > vmalloc code we do not fall to 0-order allocator if there is > > a request of getting a high-order. > > This isn't true, we _do_ fallback to order-0 (this is the basis of my patch), in > __vmalloc_node_range():- > > /* Allocate physical pages and map them into vmalloc space. */ > ret = __vmalloc_area_node(area, gfp_mask, prot, shift, node); > if (!ret) > goto fail; > > ... > > fail: > if (shift > PAGE_SHIFT) { > shift = PAGE_SHIFT; > align = real_align; > size = real_size; > goto again; > } > > With the order being derived from shift, and __vmalloc_area_node() only being > called from __vmalloc_node_range(). > Correct. It is done on an upper-layer whereas i checked the vm_area_alloc_pages() function. But as you mentioned, the refactoring has to be done as it looks a bit messy. -- Uladzislau Rezki
