| Message ID | 20180614063454.GA32419@hori1.linux.bs1.fc.nec.co.jp (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jun 14, 2018 at 06:34:55AM +0000, 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 +0000, 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 <n-horiguchi@ah.jp.nec.com> > 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 fffffffffffffffe > PGD 9b20e067 P4D 9b20e067 PUD 9b210067 PMD 0 > Oops: 0000 [#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:ffffbbd44111fde0 EFLAGS: 00010202 > RAX: fffffffffffffffe RBX: 00007fffffffeff9 RCX: 0000000000000000 > RDX: 0000000000000001 RSI: 0000000000000202 RDI: ffffed1182fff5c0 > RBP: ffffffffffffffff R08: 0000000000000001 R09: 0000000000000001 > R10: ffffbbd44111fed8 R11: 0000000000000000 R12: ffffed1182fff5c0 > R13: 00000000000bffd7 R14: 0000000002fff5c0 R15: ffffbbd44111ff10 > FS: 00007efc4335a500(0000) GS:ffff93a5bfc00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: fffffffffffffffe CR3: 00000000b2a58000 CR4: 00000000001406e0 > 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 = 0x00000001fff75c00 reserved size = 0x000000000300c000 > memory.cnt = 0x4 > memory[0x0] [0x0000000000001000-0x000000000009efff], 0x000000000009e000 bytes on node 0 flags: 0x0 > memory[0x1] [0x0000000000100000-0x00000000bffd6fff], 0x00000000bfed7000 bytes on node 0 flags: 0x0 > memory[0x2] [0x0000000100000000-0x000000013fffffff], 0x0000000040000000 bytes on node 0 flags: 0x0 > memory[0x3] [0x0000000140000000-0x000000023fffffff], 0x0000000100000000 bytes on node 1 flags: 0x0 > ... > > If you give memmap=1G!4G (so it just covers memory[0x2]), > the range [0x100000000-0x13fffffff] is gone: > > MEMBLOCK configuration: > memory size = 0x00000001bff75c00 reserved size = 0x000000000300c000 > memory.cnt = 0x3 > memory[0x0] [0x0000000000001000-0x000000000009efff], 0x000000000009e000 bytes on node 0 flags: 0x0 > memory[0x1] [0x0000000000100000-0x00000000bffd6fff], 0x00000000bfed7000 bytes on node 0 flags: 0x0 > memory[0x2] [0x0000000140000000-0x000000023fffffff], 0x0000000100000000 bytes on node 1 flags: 0x0 > ... > > This causes shrinking node 0's pfn range because it is calculated by > the address range of memblock.memory. So some of struct pages in the > gap range are left uninitialized. > > We have a function zero_resv_unavail() which does zeroing the struct > pages within the reserved unavailable range (i.e. memblock.memory && > !memblock.reserved). This patch utilizes it to cover all unavailable > ranges by putting them into memblock.reserved. > > Fixes: f7f99100d8d9 ("mm: stop zeroing memory during allocation in vmemmap") > Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > Suggested-by: Oscar Salvador <osalvador@techadventures.net> > Tested-by: Oscar Salvador <osalvador@techadventures.net> > --- > arch/x86/kernel/e820.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > index d1f25c831447..d15ef47ea354 100644 > --- a/arch/x86/kernel/e820.c > +++ b/arch/x86/kernel/e820.c > @@ -1248,6 +1248,7 @@ void __init e820__memblock_setup(void) > { > int i; > u64 end; > + u64 next = 0; > > /* > * The bootstrap memblock region count maximum is 128 entries > @@ -1270,6 +1271,17 @@ void __init e820__memblock_setup(void) > if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN) > continue; > > + /* > + * Ranges unavailable in E820_TYPE_RAM are put into > + * memblock.reserved, to make sure that struct pages in such > + * regions are not left uninitialized after bootup. > + */ > + if (entry->type == E820_TYPE_RAM) > + if (next < entry->addr) { > + memblock_reserve (next, next + (entry->addr - next)); > + next = end; > + } > + > memblock_add(entry->addr, entry->size); > } Thanks Naoya! Andrew: In case you consider to take this patch instead of the first one, could you please replace "osalvador@techadventures.net" with "osalvador@suse.de"? Thanks Best Regards Oscar Salvador
On Thu, Jun 14, 2018 at 09:21:03AM +0200, Oscar Salvador wrote: > On Thu, Jun 14, 2018 at 06:34:55AM +0000, 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 +0000, 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 <n-horiguchi@ah.jp.nec.com> > > 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 fffffffffffffffe > > PGD 9b20e067 P4D 9b20e067 PUD 9b210067 PMD 0 > > Oops: 0000 [#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:ffffbbd44111fde0 EFLAGS: 00010202 > > RAX: fffffffffffffffe RBX: 00007fffffffeff9 RCX: 0000000000000000 > > RDX: 0000000000000001 RSI: 0000000000000202 RDI: ffffed1182fff5c0 > > RBP: ffffffffffffffff R08: 0000000000000001 R09: 0000000000000001 > > R10: ffffbbd44111fed8 R11: 0000000000000000 R12: ffffed1182fff5c0 > > R13: 00000000000bffd7 R14: 0000000002fff5c0 R15: ffffbbd44111ff10 > > FS: 00007efc4335a500(0000) GS:ffff93a5bfc00000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: fffffffffffffffe CR3: 00000000b2a58000 CR4: 00000000001406e0 > > 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 = 0x00000001fff75c00 reserved size = 0x000000000300c000 > > memory.cnt = 0x4 > > memory[0x0] [0x0000000000001000-0x000000000009efff], 0x000000000009e000 bytes on node 0 flags: 0x0 > > memory[0x1] [0x0000000000100000-0x00000000bffd6fff], 0x00000000bfed7000 bytes on node 0 flags: 0x0 > > memory[0x2] [0x0000000100000000-0x000000013fffffff], 0x0000000040000000 bytes on node 0 flags: 0x0 > > memory[0x3] [0x0000000140000000-0x000000023fffffff], 0x0000000100000000 bytes on node 1 flags: 0x0 > > ... > > > > If you give memmap=1G!4G (so it just covers memory[0x2]), > > the range [0x100000000-0x13fffffff] is gone: > > > > MEMBLOCK configuration: > > memory size = 0x00000001bff75c00 reserved size = 0x000000000300c000 > > memory.cnt = 0x3 > > memory[0x0] [0x0000000000001000-0x000000000009efff], 0x000000000009e000 bytes on node 0 flags: 0x0 > > memory[0x1] [0x0000000000100000-0x00000000bffd6fff], 0x00000000bfed7000 bytes on node 0 flags: 0x0 > > memory[0x2] [0x0000000140000000-0x000000023fffffff], 0x0000000100000000 bytes on node 1 flags: 0x0 > > ... > > > > This causes shrinking node 0's pfn range because it is calculated by > > the address range of memblock.memory. So some of struct pages in the > > gap range are left uninitialized. > > > > We have a function zero_resv_unavail() which does zeroing the struct > > pages within the reserved unavailable range (i.e. memblock.memory && > > !memblock.reserved). This patch utilizes it to cover all unavailable > > ranges by putting them into memblock.reserved. I just spotted this. It seems that the changelog has not been updated. It still refers to zero_resv_unavail(), while this patch takes a different approach. > > > > Fixes: f7f99100d8d9 ("mm: stop zeroing memory during allocation in vmemmap") > > Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > > Suggested-by: Oscar Salvador <osalvador@techadventures.net> > > Tested-by: Oscar Salvador <osalvador@techadventures.net> > > --- > > arch/x86/kernel/e820.c | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > > index d1f25c831447..d15ef47ea354 100644 > > --- a/arch/x86/kernel/e820.c > > +++ b/arch/x86/kernel/e820.c > > @@ -1248,6 +1248,7 @@ void __init e820__memblock_setup(void) > > { > > int i; > > u64 end; > > + u64 next = 0; > > > > /* > > * The bootstrap memblock region count maximum is 128 entries > > @@ -1270,6 +1271,17 @@ void __init e820__memblock_setup(void) > > if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN) > > continue; > > > > + /* > > + * Ranges unavailable in E820_TYPE_RAM are put into > > + * memblock.reserved, to make sure that struct pages in such > > + * regions are not left uninitialized after bootup. > > + */ > > + if (entry->type == E820_TYPE_RAM) > > + if (next < entry->addr) { > > + memblock_reserve (next, next + (entry->addr - next)); > > + next = end; > > + } > > + > > memblock_add(entry->addr, entry->size); > > } > > Thanks Naoya! > > Andrew: In case you consider to take this patch instead of the first one, > could you please replace "osalvador@techadventures.net" with "osalvador@suse.de"? > > Thanks > > Best Regards > Oscar Salvador > Best Regards Oscar Salvador
On Thu, Jun 14, 2018 at 06:34:55AM +0000, 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 +0000, 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 <n-horiguchi@ah.jp.nec.com> > 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 fffffffffffffffe > PGD 9b20e067 P4D 9b20e067 PUD 9b210067 PMD 0 > Oops: 0000 [#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:ffffbbd44111fde0 EFLAGS: 00010202 > RAX: fffffffffffffffe RBX: 00007fffffffeff9 RCX: 0000000000000000 > RDX: 0000000000000001 RSI: 0000000000000202 RDI: ffffed1182fff5c0 > RBP: ffffffffffffffff R08: 0000000000000001 R09: 0000000000000001 > R10: ffffbbd44111fed8 R11: 0000000000000000 R12: ffffed1182fff5c0 > R13: 00000000000bffd7 R14: 0000000002fff5c0 R15: ffffbbd44111ff10 > FS: 00007efc4335a500(0000) GS:ffff93a5bfc00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: fffffffffffffffe CR3: 00000000b2a58000 CR4: 00000000001406e0 > 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 = 0x00000001fff75c00 reserved size = 0x000000000300c000 > memory.cnt = 0x4 > memory[0x0] [0x0000000000001000-0x000000000009efff], 0x000000000009e000 bytes on node 0 flags: 0x0 > memory[0x1] [0x0000000000100000-0x00000000bffd6fff], 0x00000000bfed7000 bytes on node 0 flags: 0x0 > memory[0x2] [0x0000000100000000-0x000000013fffffff], 0x0000000040000000 bytes on node 0 flags: 0x0 > memory[0x3] [0x0000000140000000-0x000000023fffffff], 0x0000000100000000 bytes on node 1 flags: 0x0 > ... > > If you give memmap=1G!4G (so it just covers memory[0x2]), > the range [0x100000000-0x13fffffff] is gone: > > MEMBLOCK configuration: > memory size = 0x00000001bff75c00 reserved size = 0x000000000300c000 > memory.cnt = 0x3 > memory[0x0] [0x0000000000001000-0x000000000009efff], 0x000000000009e000 bytes on node 0 flags: 0x0 > memory[0x1] [0x0000000000100000-0x00000000bffd6fff], 0x00000000bfed7000 bytes on node 0 flags: 0x0 > memory[0x2] [0x0000000140000000-0x000000023fffffff], 0x0000000100000000 bytes on node 1 flags: 0x0 > ... > > This causes shrinking node 0's pfn range because it is calculated by > the address range of memblock.memory. So some of struct pages in the > gap range are left uninitialized. > > We have a function zero_resv_unavail() which does zeroing the struct > pages within the reserved unavailable range (i.e. memblock.memory && > !memblock.reserved). This patch utilizes it to cover all unavailable > ranges by putting them into memblock.reserved. > > Fixes: f7f99100d8d9 ("mm: stop zeroing memory during allocation in vmemmap") > Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > Suggested-by: Oscar Salvador <osalvador@techadventures.net> > Tested-by: Oscar Salvador <osalvador@techadventures.net> > --- > arch/x86/kernel/e820.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > index d1f25c831447..d15ef47ea354 100644 > --- a/arch/x86/kernel/e820.c > +++ b/arch/x86/kernel/e820.c > @@ -1248,6 +1248,7 @@ void __init e820__memblock_setup(void) > { > int i; > u64 end; > + u64 next = 0; > > /* > * The bootstrap memblock region count maximum is 128 entries > @@ -1270,6 +1271,17 @@ void __init e820__memblock_setup(void) > if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN) > continue; > > + /* > + * Ranges unavailable in E820_TYPE_RAM are put into > + * memblock.reserved, to make sure that struct pages in such > + * regions are not left uninitialized after bootup. > + */ > + if (entry->type == E820_TYPE_RAM) > + if (next < entry->addr) { > + memblock_reserve (next, next + (entry->addr - next)); > + next = end; > + } > + > memblock_add(entry->addr, entry->size); > } Sorry, but this patch is broken. While I do not get the failure, it somehow cuts the memory down. I did not have time to check why. So I think that for now we should stick to your patch that touches the same code: ======= @@ -1248,6 +1276,8 @@ void __init e820__memblock_setup(void) { int i; u64 end; + u64 next; + u64 addr = 0; /* * The bootstrap memblock region count maximum is 128 entries @@ -1260,17 +1290,21 @@ void __init e820__memblock_setup(void) */ memblock_allow_resize(); for (i = 0; i < e820_table->nr_entries; i++) { struct e820_entry *entry = &e820_table->entries[i]; end = entry->addr + entry->size; + if (addr < entry->addr) + memblock_reserve(addr, entry->addr - addr); + addr = end; if (end != (resource_size_t)end) continue; if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN) - continue; - - memblock_add(entry->addr, entry->size); + memblock_reserve(entry->addr, entry->size); + else + memblock_add(entry->addr, entry->size); ======= I checked it, and with that version everything looks fine. > > -- > 2.7.4 > Best Regards Oscar Salvador
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 +0000, 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 +0000, 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 <n-horiguchi@ah.jp.nec.com> > > > 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 fffffffffffffffe > > > PGD 9b20e067 P4D 9b20e067 PUD 9b210067 PMD 0 > > > Oops: 0000 [#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:ffffbbd44111fde0 EFLAGS: 00010202 > > > RAX: fffffffffffffffe RBX: 00007fffffffeff9 RCX: 0000000000000000 > > > RDX: 0000000000000001 RSI: 0000000000000202 RDI: ffffed1182fff5c0 > > > RBP: ffffffffffffffff R08: 0000000000000001 R09: 0000000000000001 > > > R10: ffffbbd44111fed8 R11: 0000000000000000 R12: ffffed1182fff5c0 > > > R13: 00000000000bffd7 R14: 0000000002fff5c0 R15: ffffbbd44111ff10 > > > FS: 00007efc4335a500(0000) GS:ffff93a5bfc00000(0000) knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: fffffffffffffffe CR3: 00000000b2a58000 CR4: 00000000001406e0 > > > 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 = 0x00000001fff75c00 reserved size = 0x000000000300c000 > > > memory.cnt = 0x4 > > > memory[0x0] [0x0000000000001000-0x000000000009efff], 0x000000000009e000 bytes on node 0 flags: 0x0 > > > memory[0x1] [0x0000000000100000-0x00000000bffd6fff], 0x00000000bfed7000 bytes on node 0 flags: 0x0 > > > memory[0x2] [0x0000000100000000-0x000000013fffffff], 0x0000000040000000 bytes on node 0 flags: 0x0 > > > memory[0x3] [0x0000000140000000-0x000000023fffffff], 0x0000000100000000 bytes on node 1 flags: 0x0 > > > ... > > > > > > If you give memmap=1G!4G (so it just covers memory[0x2]), > > > the range [0x100000000-0x13fffffff] is gone: > > > > > > MEMBLOCK configuration: > > > memory size = 0x00000001bff75c00 reserved size = 0x000000000300c000 > > > memory.cnt = 0x3 > > > memory[0x0] [0x0000000000001000-0x000000000009efff], 0x000000000009e000 bytes on node 0 flags: 0x0 > > > memory[0x1] [0x0000000000100000-0x00000000bffd6fff], 0x00000000bfed7000 bytes on node 0 flags: 0x0 > > > memory[0x2] [0x0000000140000000-0x000000023fffffff], 0x0000000100000000 bytes on node 1 flags: 0x0 > > > ... > > > > > > This causes shrinking node 0's pfn range because it is calculated by > > > the address range of memblock.memory. So some of struct pages in the > > > gap range are left uninitialized. > > > > > > We have a function zero_resv_unavail() which does zeroing the struct > > > pages within the reserved unavailable range (i.e. memblock.memory && > > > !memblock.reserved). This patch utilizes it to cover all unavailable > > > ranges by putting them into memblock.reserved. > > I just spotted this. > It seems that the changelog has not been updated. > It still refers to zero_resv_unavail(), while this patch takes > a different approach. Actually I updated this paragraph a little. v1 changes zero_resv_unavail() itself to do zeroing every range outside memblock.memory!. And v2 keeps zero_resv_unavail() as is, but by newly putting some ranges into memblock.reserved, the ranges become to be handled by zero_resv_unavail(), so I still mention this function. It seems that with current patch we zero twice in zero_resv_unavail() and reserve_bootmem_region(), so there might be a room of improvement to remove the duplicate. Thanks, Naoya Horiguchi > > > > > > > Fixes: f7f99100d8d9 ("mm: stop zeroing memory during allocation in vmemmap") > > > Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > > > Suggested-by: Oscar Salvador <osalvador@techadventures.net> > > > Tested-by: Oscar Salvador <osalvador@techadventures.net> > > > --- > > > arch/x86/kernel/e820.c | 12 ++++++++++++ > > > 1 file changed, 12 insertions(+) > > > > > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > > > index d1f25c831447..d15ef47ea354 100644 > > > --- a/arch/x86/kernel/e820.c > > > +++ b/arch/x86/kernel/e820.c > > > @@ -1248,6 +1248,7 @@ void __init e820__memblock_setup(void) > > > { > > > int i; > > > u64 end; > > > + u64 next = 0; > > > > > > /* > > > * The bootstrap memblock region count maximum is 128 entries > > > @@ -1270,6 +1271,17 @@ void __init e820__memblock_setup(void) > > > if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN) > > > continue; > > > > > > + /* > > > + * Ranges unavailable in E820_TYPE_RAM are put into > > > + * memblock.reserved, to make sure that struct pages in such > > > + * regions are not left uninitialized after bootup. > > > + */ > > > + if (entry->type == E820_TYPE_RAM) > > > + if (next < entry->addr) { > > > + memblock_reserve (next, next + (entry->addr - next)); > > > + next = end; > > > + } > > > + > > > memblock_add(entry->addr, entry->size); > > > } > > > > Thanks Naoya! > > > > Andrew: In case you consider to take this patch instead of the first one, > > could you please replace "osalvador@techadventures.net" with "osalvador@suse.de"? > > > > Thanks > > > > Best Regards > > Oscar Salvador > > > > Best Regards > Oscar Salvador >
On Thu, Jun 14, 2018 at 11:30:34PM +0200, Oscar Salvador wrote: > On Thu, Jun 14, 2018 at 06:34:55AM +0000, 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 +0000, 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 <n-horiguchi@ah.jp.nec.com> > > 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 fffffffffffffffe > > PGD 9b20e067 P4D 9b20e067 PUD 9b210067 PMD 0 > > Oops: 0000 [#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:ffffbbd44111fde0 EFLAGS: 00010202 > > RAX: fffffffffffffffe RBX: 00007fffffffeff9 RCX: 0000000000000000 > > RDX: 0000000000000001 RSI: 0000000000000202 RDI: ffffed1182fff5c0 > > RBP: ffffffffffffffff R08: 0000000000000001 R09: 0000000000000001 > > R10: ffffbbd44111fed8 R11: 0000000000000000 R12: ffffed1182fff5c0 > > R13: 00000000000bffd7 R14: 0000000002fff5c0 R15: ffffbbd44111ff10 > > FS: 00007efc4335a500(0000) GS:ffff93a5bfc00000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: fffffffffffffffe CR3: 00000000b2a58000 CR4: 00000000001406e0 > > 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 = 0x00000001fff75c00 reserved size = 0x000000000300c000 > > memory.cnt = 0x4 > > memory[0x0] [0x0000000000001000-0x000000000009efff], 0x000000000009e000 bytes on node 0 flags: 0x0 > > memory[0x1] [0x0000000000100000-0x00000000bffd6fff], 0x00000000bfed7000 bytes on node 0 flags: 0x0 > > memory[0x2] [0x0000000100000000-0x000000013fffffff], 0x0000000040000000 bytes on node 0 flags: 0x0 > > memory[0x3] [0x0000000140000000-0x000000023fffffff], 0x0000000100000000 bytes on node 1 flags: 0x0 > > ... > > > > If you give memmap=1G!4G (so it just covers memory[0x2]), > > the range [0x100000000-0x13fffffff] is gone: > > > > MEMBLOCK configuration: > > memory size = 0x00000001bff75c00 reserved size = 0x000000000300c000 > > memory.cnt = 0x3 > > memory[0x0] [0x0000000000001000-0x000000000009efff], 0x000000000009e000 bytes on node 0 flags: 0x0 > > memory[0x1] [0x0000000000100000-0x00000000bffd6fff], 0x00000000bfed7000 bytes on node 0 flags: 0x0 > > memory[0x2] [0x0000000140000000-0x000000023fffffff], 0x0000000100000000 bytes on node 1 flags: 0x0 > > ... > > > > This causes shrinking node 0's pfn range because it is calculated by > > the address range of memblock.memory. So some of struct pages in the > > gap range are left uninitialized. > > > > We have a function zero_resv_unavail() which does zeroing the struct > > pages within the reserved unavailable range (i.e. memblock.memory && > > !memblock.reserved). This patch utilizes it to cover all unavailable > > ranges by putting them into memblock.reserved. > > > > Fixes: f7f99100d8d9 ("mm: stop zeroing memory during allocation in vmemmap") > > Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > > Suggested-by: Oscar Salvador <osalvador@techadventures.net> > > Tested-by: Oscar Salvador <osalvador@techadventures.net> > > --- > > arch/x86/kernel/e820.c | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > > index d1f25c831447..d15ef47ea354 100644 > > --- a/arch/x86/kernel/e820.c > > +++ b/arch/x86/kernel/e820.c > > @@ -1248,6 +1248,7 @@ void __init e820__memblock_setup(void) > > { > > int i; > > u64 end; > > + u64 next = 0; > > > > /* > > * The bootstrap memblock region count maximum is 128 entries > > @@ -1270,6 +1271,17 @@ void __init e820__memblock_setup(void) > > if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN) > > continue; > > > > + /* > > + * Ranges unavailable in E820_TYPE_RAM are put into > > + * memblock.reserved, to make sure that struct pages in such > > + * regions are not left uninitialized after bootup. > > + */ > > + if (entry->type == E820_TYPE_RAM) > > + if (next < entry->addr) { > > + memblock_reserve (next, next + (entry->addr - next)); > > + next = end; > > + } > > + > > memblock_add(entry->addr, entry->size); > > } > > Sorry, but this patch is broken. > While I do not get the failure, it somehow cuts the memory down. > I did not have time to check why. > > So I think that for now we should stick to your patch that touches the same code: > > ======= > @@ -1248,6 +1276,8 @@ void __init e820__memblock_setup(void) > { > int i; > u64 end; > + u64 next; > + u64 addr = 0; > > /* > * The bootstrap memblock region count maximum is 128 entries > @@ -1260,17 +1290,21 @@ void __init e820__memblock_setup(void) > */ > memblock_allow_resize(); > > for (i = 0; i < e820_table->nr_entries; i++) { > struct e820_entry *entry = &e820_table->entries[i]; > > end = entry->addr + entry->size; > + if (addr < entry->addr) > + memblock_reserve(addr, entry->addr - addr); > + addr = end; > if (end != (resource_size_t)end) > continue; > > if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN) > - continue; > - > - memblock_add(entry->addr, entry->size); > + memblock_reserve(entry->addr, entry->size); > + else > + memblock_add(entry->addr, entry->size); > ======= > > I checked it, and with that version everything looks fine. OK, I'll go back to this version. Thanks, Naoya Horiguchi
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index d1f25c831447..d15ef47ea354 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -1248,6 +1248,7 @@ void __init e820__memblock_setup(void) { int i; u64 end; + u64 next = 0; /* * The bootstrap memblock region count maximum is 128 entries @@ -1270,6 +1271,17 @@ void __init e820__memblock_setup(void) if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN) continue; + /* + * Ranges unavailable in E820_TYPE_RAM are put into + * memblock.reserved, to make sure that struct pages in such + * regions are not left uninitialized after bootup. + */ + if (entry->type == E820_TYPE_RAM) + if (next < entry->addr) { + memblock_reserve (next, next + (entry->addr - next)); + next = end; + } + memblock_add(entry->addr, entry->size); }