Re: [PATCH v2] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved
On Thu, Jun 14, 2018 at 11:30:34PM +0200, Oscar Salvador wrote: > On Thu, Jun 14, 2018 at 06:34:55AM +, Naoya Horiguchi wrote: > > On Thu, Jun 14, 2018 at 07:38:59AM +0200, Oscar Salvador wrote: > > > On Thu, Jun 14, 2018 at 05:16:18AM +, Naoya Horiguchi wrote: > > ... > > > > > > > > My concern is that there are a few E820 memory types rather than > > > > E820_TYPE_RAM and E820_TYPE_RESERVED, and I'm not sure that putting them > > > > all into memblock.reserved is really acceptable. > > > > > > Hi Naoya, > > > > > > Maybe you could just add to memblock.reserved, all unavailable ranges > > > within > > > E820_TYPE_RAM. > > > Actually, in your original patch, you are walking memblock.memory, which > > > should > > > only contain E820_TYPE_RAM ranges (talking about x86). > > > > > > So I think the below would to the trick as well? > > > > > > @@ -1248,6 +1276,7 @@ void __init e820__memblock_setup(void) > > > { > > > int i; > > > u64 end; > > > + u64 next = 0; > > > > > > /* > > > * The bootstrap memblock region count maximum is 128 entries > > > > > > @@ -1269,6 +1299,14 @@ void __init e820__memblock_setup(void) > > > > > > if (entry->type != E820_TYPE_RAM && entry->type != > > > E820_TYPE_RESERVED_KERN) > > > continue; > > > > > > + > > > + if (entry->type == E820_TYPE_RAM) > > > + if (next < entry->addr) { > > > + memblock_reserve (next, next + (entry->addr - > > > next)); > > > + next = end; > > > + } > > > > > > With the above patch, I can no longer see the issues either. > > > > I double-checked and this change looks good to me. > > > > > > > > Although, there is a difference between this and your original patch. > > > In your original patch, you are just zeroing the pages, while with this > > > one (or with your second patch), > > > we will zero the page in reserve_bootmem_region(), but that function also > > > init > > > some other fields of the struct page: > > > > > > mm_zero_struct_page(page); > > > set_page_links(page, zone, nid, pfn); > > > init_page_count(page); > > > page_mapcount_reset(page); > > > page_cpupid_reset_last(page); > > > > > > So I am not sure we want to bother doing that for pages that are really > > > unreachable. > > > > I think that considering that /proc/kpageflags can check them, some data > > (even if it's trivial) might be better than just zeros. > > > > Here's the updated patch. > > Thanks for the suggestion and testing! > > > > --- > > From: Naoya Horiguchi > > Date: Thu, 14 Jun 2018 14:44:36 +0900 > > Subject: [PATCH] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved > > > > There is a kernel panic that is triggered when reading /proc/kpageflags > > on the kernel booted with kernel parameter 'memmap=nn[KMG]!ss[KMG]': > > > > BUG: unable to handle kernel paging request at fffe > > PGD 9b20e067 P4D 9b20e067 PUD 9b210067 PMD 0 > > Oops: [#1] SMP PTI > > CPU: 2 PID: 1728 Comm: page-types Not tainted > > 4.17.0-rc6-mm1-v4.17-rc6-180605-0816-00236-g2dfb086ef02c+ #160 > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.fc28 > > 04/01/2014 > > RIP: 0010:stable_page_flags+0x27/0x3c0 > > Code: 00 00 00 0f 1f 44 00 00 48 85 ff 0f 84 a0 03 00 00 41 54 55 49 89 > > fc 53 48 8b 57 08 48 8b 2f 48 8d 42 ff 83 e2 01 48 0f 44 c7 <48> 8b 00 f6 > > c4 01 0f 84 10 03 00 00 31 db 49 8b 54 24 08 4c 89 e7 > > RSP: 0018:bbd44111fde0 EFLAGS: 00010202 > > RAX: fffe RBX: 7fffeff9 RCX: > > RDX: 0001 RSI: 0202 RDI: ed1182fff5c0 > > RBP: R08: 0001 R09: 0001 > > R10: bbd44111fed8 R11: R12: ed1182fff5c0 > > R13: 000bffd7 R14: 02fff5c0 R15: bbd44111ff10 > > FS: 7efc4335a500() GS:93a5bfc0() > > knlGS: > > CS: 0010 DS: ES: CR0: 80050033 > > CR2: fffe CR3: b2a58000 CR4: 001406e0 > > Call Trace: > >kpageflags_read+0xc7/0x120 > >proc_reg_read+0x3c/0x60 > >__vfs_read+0x36/0x170 > >vfs_read+0x89/0x130 > >ksys_pread64+0x71/0x90 > >do_syscall_64+0x5b/0x160 > >entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > RIP: 0033:0x7efc42e75e23 > > Code: 09 00 ba 9f 01 00 00 e8 ab 81 f4 ff 66 2e 0f 1f 84 00 00 00 00 00 > > 90 83 3d 29 0a 2d 00 00 75 13 49 89 ca b8 11 00 00 00 0f 05 <48> 3d 01 f0 > > ff ff 73 34 c3 48 83 ec 08 e8 db d3 01 00 48 89 04 24 > > > > According to kernel bisection, this problem became visible due to commit > > f7f99100d8d9 which changes how struct pages are initialized. > > > > Memblock layout affects the pfn ranges covered by node/zone. Consider > > that we have a VM with 2 NUMA nodes and each node has 4GB memory, and > > the
Re: [PATCH v2] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved
On Thu, Jun 14, 2018 at 01:24:37PM +0200, Oscar Salvador wrote: > On Thu, Jun 14, 2018 at 09:21:03AM +0200, Oscar Salvador wrote: > > On Thu, Jun 14, 2018 at 06:34:55AM +, Naoya Horiguchi wrote: > > > On Thu, Jun 14, 2018 at 07:38:59AM +0200, Oscar Salvador wrote: > > > > On Thu, Jun 14, 2018 at 05:16:18AM +, Naoya Horiguchi wrote: > > > ... > > > > > > > > > > My concern is that there are a few E820 memory types rather than > > > > > E820_TYPE_RAM and E820_TYPE_RESERVED, and I'm not sure that putting > > > > > them > > > > > all into memblock.reserved is really acceptable. > > > > > > > > Hi Naoya, > > > > > > > > Maybe you could just add to memblock.reserved, all unavailable ranges > > > > within > > > > E820_TYPE_RAM. > > > > Actually, in your original patch, you are walking memblock.memory, > > > > which should > > > > only contain E820_TYPE_RAM ranges (talking about x86). > > > > > > > > So I think the below would to the trick as well? > > > > > > > > @@ -1248,6 +1276,7 @@ void __init e820__memblock_setup(void) > > > > { > > > > int i; > > > > u64 end; > > > > + u64 next = 0; > > > > > > > > /* > > > > * The bootstrap memblock region count maximum is 128 entries > > > > > > > > @@ -1269,6 +1299,14 @@ void __init e820__memblock_setup(void) > > > > > > > > if (entry->type != E820_TYPE_RAM && entry->type != > > > > E820_TYPE_RESERVED_KERN) > > > > continue; > > > > > > > > + > > > > + if (entry->type == E820_TYPE_RAM) > > > > + if (next < entry->addr) { > > > > + memblock_reserve (next, next + > > > > (entry->addr - next)); > > > > + next = end; > > > > + } > > > > > > > > With the above patch, I can no longer see the issues either. > > > > > > I double-checked and this change looks good to me. > > > > > > > > > > > Although, there is a difference between this and your original patch. > > > > In your original patch, you are just zeroing the pages, while with this > > > > one (or with your second patch), > > > > we will zero the page in reserve_bootmem_region(), but that function > > > > also init > > > > some other fields of the struct page: > > > > > > > > mm_zero_struct_page(page); > > > > set_page_links(page, zone, nid, pfn); > > > > init_page_count(page); > > > > page_mapcount_reset(page); > > > > page_cpupid_reset_last(page); > > > > > > > > So I am not sure we want to bother doing that for pages that are really > > > > unreachable. > > > > > > I think that considering that /proc/kpageflags can check them, some data > > > (even if it's trivial) might be better than just zeros. > > > > > > Here's the updated patch. > > > Thanks for the suggestion and testing! > > > > > > --- > > > From: Naoya Horiguchi > > > Date: Thu, 14 Jun 2018 14:44:36 +0900 > > > Subject: [PATCH] x86/e820: put !E820_TYPE_RAM regions into > > > memblock.reserved > > > > > > There is a kernel panic that is triggered when reading /proc/kpageflags > > > on the kernel booted with kernel parameter 'memmap=nn[KMG]!ss[KMG]': > > > > > > BUG: unable to handle kernel paging request at fffe > > > PGD 9b20e067 P4D 9b20e067 PUD 9b210067 PMD 0 > > > Oops: [#1] SMP PTI > > > CPU: 2 PID: 1728 Comm: page-types Not tainted > > > 4.17.0-rc6-mm1-v4.17-rc6-180605-0816-00236-g2dfb086ef02c+ #160 > > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > > > 1.11.0-2.fc28 04/01/2014 > > > RIP: 0010:stable_page_flags+0x27/0x3c0 > > > Code: 00 00 00 0f 1f 44 00 00 48 85 ff 0f 84 a0 03 00 00 41 54 55 49 89 > > > fc 53 48 8b 57 08 48 8b 2f 48 8d 42 ff 83 e2 01 48 0f 44 c7 <48> 8b 00 f6 > > > c4 01 0f 84 10 03 00 00 31 db 49 8b 54 24 08 4c 89 e7 > > > RSP: 0018:bbd44111fde0 EFLAGS: 00010202 > > > RAX: fffe RBX: 7fffeff9 RCX: > > > RDX: 0001 RSI: 0202 RDI: ed1182fff5c0 > > > RBP: R08: 0001 R09: 0001 > > > R10: bbd44111fed8 R11: R12: ed1182fff5c0 > > > R13: 000bffd7 R14: 02fff5c0 R15: bbd44111ff10 > > > FS: 7efc4335a500() GS:93a5bfc0() > > > knlGS: > > > CS: 0010 DS: ES: CR0: 80050033 > > > CR2: fffe CR3: b2a58000 CR4: 001406e0 > > > Call Trace: > > >kpageflags_read+0xc7/0x120 > > >proc_reg_read+0x3c/0x60 > > >__vfs_read+0x36/0x170 > > >vfs_read+0x89/0x130 > > >ksys_pread64+0x71/0x90 > > >do_syscall_64+0x5b/0x160 > > >entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > > RIP: 0033:0x7efc42e75e23 > > > Code: 09 00 ba 9f 01 00 00 e8 ab 81 f4 ff 66 2e 0f 1f 84 00 00 00 00 00 > > > 90 83 3d 29 0a 2d 00 00 75 13 49 89 ca b8 11 00 00 00 0f 05 <48> 3d 01 f0 > > > ff ff 73 34 c3 48 83 ec 08 e8 db d3 01
Re: [PATCH v2] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved
On Thu, Jun 14, 2018 at 06:34:55AM +, Naoya Horiguchi wrote: > On Thu, Jun 14, 2018 at 07:38:59AM +0200, Oscar Salvador wrote: > > On Thu, Jun 14, 2018 at 05:16:18AM +, Naoya Horiguchi wrote: > ... > > > > > > My concern is that there are a few E820 memory types rather than > > > E820_TYPE_RAM and E820_TYPE_RESERVED, and I'm not sure that putting them > > > all into memblock.reserved is really acceptable. > > > > Hi Naoya, > > > > Maybe you could just add to memblock.reserved, all unavailable ranges within > > E820_TYPE_RAM. > > Actually, in your original patch, you are walking memblock.memory, which > > should > > only contain E820_TYPE_RAM ranges (talking about x86). > > > > So I think the below would to the trick as well? > > > > @@ -1248,6 +1276,7 @@ void __init e820__memblock_setup(void) > > { > > int i; > > u64 end; > > + u64 next = 0; > > > > /* > > * The bootstrap memblock region count maximum is 128 entries > > > > @@ -1269,6 +1299,14 @@ void __init e820__memblock_setup(void) > > > > if (entry->type != E820_TYPE_RAM && entry->type != > > E820_TYPE_RESERVED_KERN) > > continue; > > > > + > > + if (entry->type == E820_TYPE_RAM) > > + if (next < entry->addr) { > > + memblock_reserve (next, next + (entry->addr - > > next)); > > + next = end; > > + } > > > > With the above patch, I can no longer see the issues either. > > I double-checked and this change looks good to me. > > > > > Although, there is a difference between this and your original patch. > > In your original patch, you are just zeroing the pages, while with this one > > (or with your second patch), > > we will zero the page in reserve_bootmem_region(), but that function also > > init > > some other fields of the struct page: > > > > mm_zero_struct_page(page); > > set_page_links(page, zone, nid, pfn); > > init_page_count(page); > > page_mapcount_reset(page); > > page_cpupid_reset_last(page); > > > > So I am not sure we want to bother doing that for pages that are really > > unreachable. > > I think that considering that /proc/kpageflags can check them, some data > (even if it's trivial) might be better than just zeros. > > Here's the updated patch. > Thanks for the suggestion and testing! > > --- > From: Naoya Horiguchi > Date: Thu, 14 Jun 2018 14:44:36 +0900 > Subject: [PATCH] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved > > There is a kernel panic that is triggered when reading /proc/kpageflags > on the kernel booted with kernel parameter 'memmap=nn[KMG]!ss[KMG]': > > BUG: unable to handle kernel paging request at fffe > PGD 9b20e067 P4D 9b20e067 PUD 9b210067 PMD 0 > Oops: [#1] SMP PTI > CPU: 2 PID: 1728 Comm: page-types Not tainted > 4.17.0-rc6-mm1-v4.17-rc6-180605-0816-00236-g2dfb086ef02c+ #160 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.fc28 > 04/01/2014 > RIP: 0010:stable_page_flags+0x27/0x3c0 > Code: 00 00 00 0f 1f 44 00 00 48 85 ff 0f 84 a0 03 00 00 41 54 55 49 89 fc > 53 48 8b 57 08 48 8b 2f 48 8d 42 ff 83 e2 01 48 0f 44 c7 <48> 8b 00 f6 c4 01 > 0f 84 10 03 00 00 31 db 49 8b 54 24 08 4c 89 e7 > RSP: 0018:bbd44111fde0 EFLAGS: 00010202 > RAX: fffe RBX: 7fffeff9 RCX: > RDX: 0001 RSI: 0202 RDI: ed1182fff5c0 > RBP: R08: 0001 R09: 0001 > R10: bbd44111fed8 R11: R12: ed1182fff5c0 > R13: 000bffd7 R14: 02fff5c0 R15: bbd44111ff10 > FS: 7efc4335a500() GS:93a5bfc0() knlGS: > CS: 0010 DS: ES: CR0: 80050033 > CR2: fffe CR3: b2a58000 CR4: 001406e0 > Call Trace: >kpageflags_read+0xc7/0x120 >proc_reg_read+0x3c/0x60 >__vfs_read+0x36/0x170 >vfs_read+0x89/0x130 >ksys_pread64+0x71/0x90 >do_syscall_64+0x5b/0x160 >entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x7efc42e75e23 > Code: 09 00 ba 9f 01 00 00 e8 ab 81 f4 ff 66 2e 0f 1f 84 00 00 00 00 00 90 > 83 3d 29 0a 2d 00 00 75 13 49 89 ca b8 11 00 00 00 0f 05 <48> 3d 01 f0 ff ff > 73 34 c3 48 83 ec 08 e8 db d3 01 00 48 89 04 24 > > According to kernel bisection, this problem became visible due to commit > f7f99100d8d9 which changes how struct pages are initialized. > > Memblock layout affects the pfn ranges covered by node/zone. Consider > that we have a VM with 2 NUMA nodes and each node has 4GB memory, and > the default (no memmap= given) memblock layout is like below: > > MEMBLOCK configuration: >memory size = 0x0001fff75c00 reserved size = 0x0300c000 >memory.cnt = 0x4 >memory[0x0] [0x1000-0x0009efff], > 0x0009e000 bytes on node 0 flags: 0x0 >m
Re: [PATCH v2] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved
On Thu, Jun 14, 2018 at 09:21:03AM +0200, Oscar Salvador wrote: > On Thu, Jun 14, 2018 at 06:34:55AM +, Naoya Horiguchi wrote: > > On Thu, Jun 14, 2018 at 07:38:59AM +0200, Oscar Salvador wrote: > > > On Thu, Jun 14, 2018 at 05:16:18AM +, Naoya Horiguchi wrote: > > ... > > > > > > > > My concern is that there are a few E820 memory types rather than > > > > E820_TYPE_RAM and E820_TYPE_RESERVED, and I'm not sure that putting them > > > > all into memblock.reserved is really acceptable. > > > > > > Hi Naoya, > > > > > > Maybe you could just add to memblock.reserved, all unavailable ranges > > > within > > > E820_TYPE_RAM. > > > Actually, in your original patch, you are walking memblock.memory, which > > > should > > > only contain E820_TYPE_RAM ranges (talking about x86). > > > > > > So I think the below would to the trick as well? > > > > > > @@ -1248,6 +1276,7 @@ void __init e820__memblock_setup(void) > > > { > > > int i; > > > u64 end; > > > + u64 next = 0; > > > > > > /* > > > * The bootstrap memblock region count maximum is 128 entries > > > > > > @@ -1269,6 +1299,14 @@ void __init e820__memblock_setup(void) > > > > > > if (entry->type != E820_TYPE_RAM && entry->type != > > > E820_TYPE_RESERVED_KERN) > > > continue; > > > > > > + > > > + if (entry->type == E820_TYPE_RAM) > > > + if (next < entry->addr) { > > > + memblock_reserve (next, next + (entry->addr - > > > next)); > > > + next = end; > > > + } > > > > > > With the above patch, I can no longer see the issues either. > > > > I double-checked and this change looks good to me. > > > > > > > > Although, there is a difference between this and your original patch. > > > In your original patch, you are just zeroing the pages, while with this > > > one (or with your second patch), > > > we will zero the page in reserve_bootmem_region(), but that function also > > > init > > > some other fields of the struct page: > > > > > > mm_zero_struct_page(page); > > > set_page_links(page, zone, nid, pfn); > > > init_page_count(page); > > > page_mapcount_reset(page); > > > page_cpupid_reset_last(page); > > > > > > So I am not sure we want to bother doing that for pages that are really > > > unreachable. > > > > I think that considering that /proc/kpageflags can check them, some data > > (even if it's trivial) might be better than just zeros. > > > > Here's the updated patch. > > Thanks for the suggestion and testing! > > > > --- > > From: Naoya Horiguchi > > Date: Thu, 14 Jun 2018 14:44:36 +0900 > > Subject: [PATCH] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved > > > > There is a kernel panic that is triggered when reading /proc/kpageflags > > on the kernel booted with kernel parameter 'memmap=nn[KMG]!ss[KMG]': > > > > BUG: unable to handle kernel paging request at fffe > > PGD 9b20e067 P4D 9b20e067 PUD 9b210067 PMD 0 > > Oops: [#1] SMP PTI > > CPU: 2 PID: 1728 Comm: page-types Not tainted > > 4.17.0-rc6-mm1-v4.17-rc6-180605-0816-00236-g2dfb086ef02c+ #160 > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.fc28 > > 04/01/2014 > > RIP: 0010:stable_page_flags+0x27/0x3c0 > > Code: 00 00 00 0f 1f 44 00 00 48 85 ff 0f 84 a0 03 00 00 41 54 55 49 89 > > fc 53 48 8b 57 08 48 8b 2f 48 8d 42 ff 83 e2 01 48 0f 44 c7 <48> 8b 00 f6 > > c4 01 0f 84 10 03 00 00 31 db 49 8b 54 24 08 4c 89 e7 > > RSP: 0018:bbd44111fde0 EFLAGS: 00010202 > > RAX: fffe RBX: 7fffeff9 RCX: > > RDX: 0001 RSI: 0202 RDI: ed1182fff5c0 > > RBP: R08: 0001 R09: 0001 > > R10: bbd44111fed8 R11: R12: ed1182fff5c0 > > R13: 000bffd7 R14: 02fff5c0 R15: bbd44111ff10 > > FS: 7efc4335a500() GS:93a5bfc0() > > knlGS: > > CS: 0010 DS: ES: CR0: 80050033 > > CR2: fffe CR3: b2a58000 CR4: 001406e0 > > Call Trace: > >kpageflags_read+0xc7/0x120 > >proc_reg_read+0x3c/0x60 > >__vfs_read+0x36/0x170 > >vfs_read+0x89/0x130 > >ksys_pread64+0x71/0x90 > >do_syscall_64+0x5b/0x160 > >entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > RIP: 0033:0x7efc42e75e23 > > Code: 09 00 ba 9f 01 00 00 e8 ab 81 f4 ff 66 2e 0f 1f 84 00 00 00 00 00 > > 90 83 3d 29 0a 2d 00 00 75 13 49 89 ca b8 11 00 00 00 0f 05 <48> 3d 01 f0 > > ff ff 73 34 c3 48 83 ec 08 e8 db d3 01 00 48 89 04 24 > > > > According to kernel bisection, this problem became visible due to commit > > f7f99100d8d9 which changes how struct pages are initialized. > > > > Memblock layout affects the pfn ranges covered by node/zone. Consider > > that we have a VM with 2 NUMA nodes and each node has 4GB memory, and > > the
Re: [PATCH v2] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved
On Thu, Jun 14, 2018 at 06:34:55AM +, Naoya Horiguchi wrote: > On Thu, Jun 14, 2018 at 07:38:59AM +0200, Oscar Salvador wrote: > > On Thu, Jun 14, 2018 at 05:16:18AM +, Naoya Horiguchi wrote: > ... > > > > > > My concern is that there are a few E820 memory types rather than > > > E820_TYPE_RAM and E820_TYPE_RESERVED, and I'm not sure that putting them > > > all into memblock.reserved is really acceptable. > > > > Hi Naoya, > > > > Maybe you could just add to memblock.reserved, all unavailable ranges within > > E820_TYPE_RAM. > > Actually, in your original patch, you are walking memblock.memory, which > > should > > only contain E820_TYPE_RAM ranges (talking about x86). > > > > So I think the below would to the trick as well? > > > > @@ -1248,6 +1276,7 @@ void __init e820__memblock_setup(void) > > { > > int i; > > u64 end; > > + u64 next = 0; > > > > /* > > * The bootstrap memblock region count maximum is 128 entries > > > > @@ -1269,6 +1299,14 @@ void __init e820__memblock_setup(void) > > > > if (entry->type != E820_TYPE_RAM && entry->type != > > E820_TYPE_RESERVED_KERN) > > continue; > > > > + > > + if (entry->type == E820_TYPE_RAM) > > + if (next < entry->addr) { > > + memblock_reserve (next, next + (entry->addr - > > next)); > > + next = end; > > + } > > > > With the above patch, I can no longer see the issues either. > > I double-checked and this change looks good to me. > > > > > Although, there is a difference between this and your original patch. > > In your original patch, you are just zeroing the pages, while with this one > > (or with your second patch), > > we will zero the page in reserve_bootmem_region(), but that function also > > init > > some other fields of the struct page: > > > > mm_zero_struct_page(page); > > set_page_links(page, zone, nid, pfn); > > init_page_count(page); > > page_mapcount_reset(page); > > page_cpupid_reset_last(page); > > > > So I am not sure we want to bother doing that for pages that are really > > unreachable. > > I think that considering that /proc/kpageflags can check them, some data > (even if it's trivial) might be better than just zeros. > > Here's the updated patch. > Thanks for the suggestion and testing! > > --- > From: Naoya Horiguchi > Date: Thu, 14 Jun 2018 14:44:36 +0900 > Subject: [PATCH] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved > > There is a kernel panic that is triggered when reading /proc/kpageflags > on the kernel booted with kernel parameter 'memmap=nn[KMG]!ss[KMG]': > > BUG: unable to handle kernel paging request at fffe > PGD 9b20e067 P4D 9b20e067 PUD 9b210067 PMD 0 > Oops: [#1] SMP PTI > CPU: 2 PID: 1728 Comm: page-types Not tainted > 4.17.0-rc6-mm1-v4.17-rc6-180605-0816-00236-g2dfb086ef02c+ #160 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.fc28 > 04/01/2014 > RIP: 0010:stable_page_flags+0x27/0x3c0 > Code: 00 00 00 0f 1f 44 00 00 48 85 ff 0f 84 a0 03 00 00 41 54 55 49 89 fc > 53 48 8b 57 08 48 8b 2f 48 8d 42 ff 83 e2 01 48 0f 44 c7 <48> 8b 00 f6 c4 01 > 0f 84 10 03 00 00 31 db 49 8b 54 24 08 4c 89 e7 > RSP: 0018:bbd44111fde0 EFLAGS: 00010202 > RAX: fffe RBX: 7fffeff9 RCX: > RDX: 0001 RSI: 0202 RDI: ed1182fff5c0 > RBP: R08: 0001 R09: 0001 > R10: bbd44111fed8 R11: R12: ed1182fff5c0 > R13: 000bffd7 R14: 02fff5c0 R15: bbd44111ff10 > FS: 7efc4335a500() GS:93a5bfc0() knlGS: > CS: 0010 DS: ES: CR0: 80050033 > CR2: fffe CR3: b2a58000 CR4: 001406e0 > Call Trace: >kpageflags_read+0xc7/0x120 >proc_reg_read+0x3c/0x60 >__vfs_read+0x36/0x170 >vfs_read+0x89/0x130 >ksys_pread64+0x71/0x90 >do_syscall_64+0x5b/0x160 >entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x7efc42e75e23 > Code: 09 00 ba 9f 01 00 00 e8 ab 81 f4 ff 66 2e 0f 1f 84 00 00 00 00 00 90 > 83 3d 29 0a 2d 00 00 75 13 49 89 ca b8 11 00 00 00 0f 05 <48> 3d 01 f0 ff ff > 73 34 c3 48 83 ec 08 e8 db d3 01 00 48 89 04 24 > > According to kernel bisection, this problem became visible due to commit > f7f99100d8d9 which changes how struct pages are initialized. > > Memblock layout affects the pfn ranges covered by node/zone. Consider > that we have a VM with 2 NUMA nodes and each node has 4GB memory, and > the default (no memmap= given) memblock layout is like below: > > MEMBLOCK configuration: >memory size = 0x0001fff75c00 reserved size = 0x0300c000 >memory.cnt = 0x4 >memory[0x0] [0x1000-0x0009efff], > 0x0009e000 bytes on node 0 flags: 0x0 >m
[PATCH v2] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved
On Thu, Jun 14, 2018 at 07:38:59AM +0200, Oscar Salvador wrote: > On Thu, Jun 14, 2018 at 05:16:18AM +, Naoya Horiguchi wrote: ... > > > > My concern is that there are a few E820 memory types rather than > > E820_TYPE_RAM and E820_TYPE_RESERVED, and I'm not sure that putting them > > all into memblock.reserved is really acceptable. > > Hi Naoya, > > Maybe you could just add to memblock.reserved, all unavailable ranges within > E820_TYPE_RAM. > Actually, in your original patch, you are walking memblock.memory, which > should > only contain E820_TYPE_RAM ranges (talking about x86). > > So I think the below would to the trick as well? > > @@ -1248,6 +1276,7 @@ void __init e820__memblock_setup(void) > { > int i; > u64 end; > + u64 next = 0; > > /* > * The bootstrap memblock region count maximum is 128 entries > > @@ -1269,6 +1299,14 @@ void __init e820__memblock_setup(void) > > if (entry->type != E820_TYPE_RAM && entry->type != > E820_TYPE_RESERVED_KERN) > continue; > > + > + if (entry->type == E820_TYPE_RAM) > + if (next < entry->addr) { > + memblock_reserve (next, next + (entry->addr - > next)); > + next = end; > + } > > With the above patch, I can no longer see the issues either. I double-checked and this change looks good to me. > > Although, there is a difference between this and your original patch. > In your original patch, you are just zeroing the pages, while with this one > (or with your second patch), > we will zero the page in reserve_bootmem_region(), but that function also init > some other fields of the struct page: > > mm_zero_struct_page(page); > set_page_links(page, zone, nid, pfn); > init_page_count(page); > page_mapcount_reset(page); > page_cpupid_reset_last(page); > > So I am not sure we want to bother doing that for pages that are really > unreachable. I think that considering that /proc/kpageflags can check them, some data (even if it's trivial) might be better than just zeros. Here's the updated patch. Thanks for the suggestion and testing! --- From: Naoya Horiguchi Date: Thu, 14 Jun 2018 14:44:36 +0900 Subject: [PATCH] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved There is a kernel panic that is triggered when reading /proc/kpageflags on the kernel booted with kernel parameter 'memmap=nn[KMG]!ss[KMG]': BUG: unable to handle kernel paging request at fffe PGD 9b20e067 P4D 9b20e067 PUD 9b210067 PMD 0 Oops: [#1] SMP PTI CPU: 2 PID: 1728 Comm: page-types Not tainted 4.17.0-rc6-mm1-v4.17-rc6-180605-0816-00236-g2dfb086ef02c+ #160 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.fc28 04/01/2014 RIP: 0010:stable_page_flags+0x27/0x3c0 Code: 00 00 00 0f 1f 44 00 00 48 85 ff 0f 84 a0 03 00 00 41 54 55 49 89 fc 53 48 8b 57 08 48 8b 2f 48 8d 42 ff 83 e2 01 48 0f 44 c7 <48> 8b 00 f6 c4 01 0f 84 10 03 00 00 31 db 49 8b 54 24 08 4c 89 e7 RSP: 0018:bbd44111fde0 EFLAGS: 00010202 RAX: fffe RBX: 7fffeff9 RCX: RDX: 0001 RSI: 0202 RDI: ed1182fff5c0 RBP: R08: 0001 R09: 0001 R10: bbd44111fed8 R11: R12: ed1182fff5c0 R13: 000bffd7 R14: 02fff5c0 R15: bbd44111ff10 FS: 7efc4335a500() GS:93a5bfc0() knlGS: CS: 0010 DS: ES: CR0: 80050033 CR2: fffe CR3: b2a58000 CR4: 001406e0 Call Trace: kpageflags_read+0xc7/0x120 proc_reg_read+0x3c/0x60 __vfs_read+0x36/0x170 vfs_read+0x89/0x130 ksys_pread64+0x71/0x90 do_syscall_64+0x5b/0x160 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7efc42e75e23 Code: 09 00 ba 9f 01 00 00 e8 ab 81 f4 ff 66 2e 0f 1f 84 00 00 00 00 00 90 83 3d 29 0a 2d 00 00 75 13 49 89 ca b8 11 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 db d3 01 00 48 89 04 24 According to kernel bisection, this problem became visible due to commit f7f99100d8d9 which changes how struct pages are initialized. Memblock layout affects the pfn ranges covered by node/zone. Consider that we have a VM with 2 NUMA nodes and each node has 4GB memory, and the default (no memmap= given) memblock layout is like below: MEMBLOCK configuration: memory size = 0x0001fff75c00 reserved size = 0x0300c000 memory.cnt = 0x4 memory[0x0] [0x1000-0x0009efff], 0x0009e000 bytes on node 0 flags: 0x0 memory[0x1] [0x0010-0xbffd6fff], 0xbfed7000 bytes on node 0 flags: 0x0 memory[0x2] [0x0001-0x00013fff], 0x4000 bytes on node 0 flags: 0x0 memory[0x3] [0x00014000-0x00023fff], 0x0001 bytes on node 1