| Message ID | 20180523125555.30039-3-mhocko@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
On 05/23/2018 06:25 PM, Michal Hocko wrote: > when adding memory to a node that is currently offline. > > The VM_WARN_ON is just too loud without a good reason. In this > particular case we are doing > alloc_pages_node(node, GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN, order) > > so we do not insist on allocating from the given node (it is more a > hint) so we can fall back to any other populated node and moreover we > explicitly ask to not warn for the allocation failure. > > Soften the warning only to cases when somebody asks for the given node > explicitly by __GFP_THISNODE. node hint passed here eventually goes into __alloc_pages_nodemask() function which then picks up the applicable zonelist irrespective of the GFP flag __GFP_THISNODE. Though we can go into zones of other nodes if the present node (whose zonelist got picked up) does not have any memory in it's zones. So warning here might not be without any reason. But yes, if the request has __GFP_NOWARN it makes sense not to print any warning.
On Wed 23-05-18 19:15:51, Anshuman Khandual wrote: > On 05/23/2018 06:25 PM, Michal Hocko wrote: > > when adding memory to a node that is currently offline. > > > > The VM_WARN_ON is just too loud without a good reason. In this > > particular case we are doing > > alloc_pages_node(node, GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN, order) > > > > so we do not insist on allocating from the given node (it is more a > > hint) so we can fall back to any other populated node and moreover we > > explicitly ask to not warn for the allocation failure. > > > > Soften the warning only to cases when somebody asks for the given node > > explicitly by __GFP_THISNODE. > > node hint passed here eventually goes into __alloc_pages_nodemask() > function which then picks up the applicable zonelist irrespective of > the GFP flag __GFP_THISNODE. __GFP_THISNODE should enforce the given node without any fallbacks unless something has changed recently. > Though we can go into zones of other > nodes if the present node (whose zonelist got picked up) does not > have any memory in it's zones. So warning here might not be without > any reason. I am not sure I follow. Are you suggesting a different VM_WARN_ON?
==== when adding memory to a node that is currently offline. The VM_WARN_ON is just too loud without a good reason. In this particular case we are doing alloc_pages_node(node, GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN, order) so we do not insist on allocating from the given node (it is more a hint) so we can fall back to any other populated node and moreover we explicitly ask to not warn for the allocation failure. Soften the warning only to cases when somebody asks for the given node explicitly by __GFP_THISNODE. Reported-by: Oscar Salvador <osalvador@techadventures.net> Tested-by: Oscar Salvador <osalvador@techadventures.net> Signed-off-by: Michal Hocko <mhocko@suse.com> --- include/linux/gfp.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/gfp.h b/include/linux/gfp.h index 036846fc00a6..7f860ea29ec6 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -464,7 +464,7 @@ static inline struct page * __alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order) { VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES); - VM_WARN_ON(!node_online(nid)); + VM_WARN_ON((gfp_mask & __GFP_THISNODE) && !node_online(nid)); return __alloc_pages(gfp_mask, order, nid); }
From: Michal Hocko <mhocko@suse.com> Oscar has noticed that we splat linux kernel: WARNING: CPU: 0 PID: 64 at ./include/linux/gfp.h:467 vmemmap_alloc_block+0x4e/0xc9 [...] linux kernel: CPU: 0 PID: 64 Comm: kworker/u4:1 Tainted: G W E 4.17.0-rc5-next-20180517-1-default+ #66 linux kernel: Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014 linux kernel: Workqueue: kacpi_hotplug acpi_hotplug_work_fn linux kernel: RIP: 0010:vmemmap_alloc_block+0x4e/0xc9 linux kernel: Code: fb ff 8d 69 01 75 07 65 8b 1d 9d cb 93 7e 81 fb ff 03 00 00 76 02 0f 0b 48 63 c3 48 0f a3 05 c8 b1 b4 00 0f 92 c0 84 c0 75 02 <0f> 0b 31 c9 89 da 89 ee bf c0 06 40 01 e8 0f d1 ad ff 48 85 c0 74 linux kernel: RSP: 0018:ffffc90000d03bf0 EFLAGS: 00010246 linux kernel: RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000008 linux kernel: RDX: 0000000000000000 RSI: 0000000000000001 RDI: 00000000000001ff linux kernel: RBP: 0000000000000009 R08: 0000000000000001 R09: ffffc90000d03ae8 linux kernel: R10: 0000000000000001 R11: 0000000000000000 R12: ffffea0006000000 linux kernel: R13: ffffea0005e00000 R14: ffffea0006000000 R15: 0000000000000001 linux kernel: FS: 0000000000000000(0000) GS:ffff88013fc00000(0000) knlGS:0000000000000000 linux kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 linux kernel: CR2: 00007fa92a698018 CR3: 00000001184ce000 CR4: 00000000000006f0 linux kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 linux kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 linux kernel: Call Trace: linux kernel: vmemmap_populate+0xf2/0x2ae linux kernel: sparse_mem_map_populate+0x28/0x35 linux kernel: sparse_add_one_section+0x4c/0x187 linux kernel: __add_pages+0xe7/0x1a0 linux kernel: add_pages+0x16/0x70 linux kernel: add_memory_resource+0xa3/0x1d0 linux kernel: add_memory+0xe4/0x110 linux kernel: acpi_memory_device_add+0x134/0x2e0 linux kernel: acpi_bus_attach+0xd9/0x190 linux kernel: acpi_bus_scan+0x37/0x70 linux kernel: acpi_device_hotplug+0x389/0x4e0 linux kernel: acpi_hotplug_work_fn+0x1a/0x30 linux kernel: process_one_work+0x146/0x340 linux kernel: worker_thread+0x47/0x3e0 linux kernel: kthread+0xf5/0x130 linux kernel: ? max_active_store+0x60/0x60 linux kernel: ? kthread_bind+0x10/0x10 linux kernel: ret_from_fork+0x35/0x40 linux kernel: ---[ end trace 2e2241f4e2f2f018 ]---