| Message ID | 20180615072947.GB23273@hori1.linux.bs1.fc.nec.co.jp (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri 15-06-18 07:29:48, Naoya Horiguchi wrote: [...] > From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > Date: Thu, 14 Jun 2018 16:04:36 +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> > Tested-by: Oscar Salvador <osalvador@suse.de> OK, this makes sense to me. It is definitely much better than the original attempt. Unless I am missing something this should be correct Acked-by: Michal Hocko <mhocko@suse.com> > --- > arch/x86/kernel/e820.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > index d1f25c831447..c88c23c658c1 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 addr = 0; > > /* > * The bootstrap memblock region count maximum is 128 entries > @@ -1264,13 +1265,21 @@ void __init e820__memblock_setup(void) > 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; > > + /* > + * all !E820_TYPE_RAM ranges (including gap ranges) 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 && 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); > } > > /* Throw away partial pages: */ > -- > 2.7.4
On 18-06-15 10:41:42, Michal Hocko wrote: > On Fri 15-06-18 07:29:48, Naoya Horiguchi wrote: > [...] > > From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > > Date: Thu, 14 Jun 2018 16:04:36 +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> > > Tested-by: Oscar Salvador <osalvador@suse.de> > > OK, this makes sense to me. It is definitely much better than the > original attempt. > > Unless I am missing something this should be correct > Acked-by: Michal Hocko <mhocko@suse.com> First of all thank you Naoya for finding and root causing this issue. So, with this fix we reserve any hole and !E820_TYPE_RAM or !E820_TYPE_RESERVED_KERN in e820. I think, this will work because we do pfn_valid() check in zero_resv_unavail(), so the ranges that do not have backing struct pages will be skipped. But, I am worried on the performance implications of when the holes of invalid memory are rather large. We would have to loop through it in zero_resv_unavail() one pfn at a time. Therefore, we might also need to optimize zero_resv_unavail() a little like this: 6407 if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) 6408 continue; Add before "continue": pfn = ALIGN_DOWN(pfn, pageblock_nr_pages) + pageblock_nr_pageas - 1. At least, this way, we would skip a section of invalid memory at a time. For the patch above: Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com> But, I think the 2nd patch with the optimization above should go along this this fix. Thank you, Pasha > > > --- > > arch/x86/kernel/e820.c | 15 ++++++++++++--- > > 1 file changed, 12 insertions(+), 3 deletions(-) > > > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > > index d1f25c831447..c88c23c658c1 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 addr = 0; > > > > /* > > * The bootstrap memblock region count maximum is 128 entries > > @@ -1264,13 +1265,21 @@ void __init e820__memblock_setup(void) > > 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; > > > > + /* > > + * all !E820_TYPE_RAM ranges (including gap ranges) 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 && 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); > > } > > > > /* Throw away partial pages: */ > > -- > > 2.7.4 > > -- > Michal Hocko > SUSE Labs >
On Fri 15-06-18 10:00:00, Pavel Tatashin wrote: [...] > But, I think the 2nd patch with the optimization above should go along this > this fix. Yes, ideally with some numbers.
On Fri, Jun 15, 2018 at 10:00:00AM -0400, Pavel Tatashin wrote: > On 18-06-15 10:41:42, Michal Hocko wrote: > > On Fri 15-06-18 07:29:48, Naoya Horiguchi wrote: > > [...] > > > From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > > > Date: Thu, 14 Jun 2018 16:04:36 +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> > > > Tested-by: Oscar Salvador <osalvador@suse.de> > > > > OK, this makes sense to me. It is definitely much better than the > > original attempt. > > > > Unless I am missing something this should be correct > > Acked-by: Michal Hocko <mhocko@suse.com> > > First of all thank you Naoya for finding and root causing this issue. > > So, with this fix we reserve any hole and !E820_TYPE_RAM or > !E820_TYPE_RESERVED_KERN in e820. I think, this will work because we > do pfn_valid() check in zero_resv_unavail(), so the ranges that do not have > backing struct pages will be skipped. But, I am worried on the performance > implications of when the holes of invalid memory are rather large. We would > have to loop through it in zero_resv_unavail() one pfn at a time. > > Therefore, we might also need to optimize zero_resv_unavail() a little like > this: > > 6407 if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) > 6408 continue; > > Add before "continue": > pfn = ALIGN_DOWN(pfn, pageblock_nr_pages) + pageblock_nr_pageas - 1. > At least, this way, we would skip a section of invalid memory at a time. > > For the patch above: > Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com> > > But, I think the 2nd patch with the optimization above should go along this > this fix. Hi Pavel, I think this makes a lot of sense. Since Naoya is out until Wednesday, maybe I give it a shot next week and see if I can gather some numbers. > > Thank you, > Pasha > > > > > > --- > > > arch/x86/kernel/e820.c | 15 ++++++++++++--- > > > 1 file changed, 12 insertions(+), 3 deletions(-) > > > > > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > > > index d1f25c831447..c88c23c658c1 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 addr = 0; > > > > > > /* > > > * The bootstrap memblock region count maximum is 128 entries > > > @@ -1264,13 +1265,21 @@ void __init e820__memblock_setup(void) > > > 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; > > > > > > + /* > > > + * all !E820_TYPE_RAM ranges (including gap ranges) 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 && 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); > > > } > > > > > > /* Throw away partial pages: */ > > > -- > > > 2.7.4 > > > > -- > > Michal Hocko > > SUSE Labs > > > Best Regards Oscar Salvador
> Hi Pavel, > > I think this makes a lot of sense. > Since Naoya is out until Wednesday, maybe I give it a shot next week and see if I can gather some numbers. Hi Oscar, Thank you for the offer to do this. Since, sched_clock() is not yet initialized at the time zero_resv_unavail() is called, it is difficult to measure it during boot. But, I had x86 early boot timestamps patches handy, so I could measure, thus decided to submit the patch. http://lkml.kernel.org/r/20180615155733.1175-1-pasha.tatashin@oracle.com Thank you, Pavel > > > > > Thank you, > > Pasha > > > > > > > > > --- > > > > arch/x86/kernel/e820.c | 15 ++++++++++++--- > > > > 1 file changed, 12 insertions(+), 3 deletions(-) > > > > > > > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > > > > index d1f25c831447..c88c23c658c1 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 addr = 0; > > > > > > > > /* > > > > * The bootstrap memblock region count maximum is 128 entries > > > > @@ -1264,13 +1265,21 @@ void __init e820__memblock_setup(void) > > > > 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; > > > > > > > > + /* > > > > + * all !E820_TYPE_RAM ranges (including gap ranges) 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 && 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); > > > > } > > > > > > > > /* Throw away partial pages: */ > > > > -- > > > > 2.7.4 > > > > > > -- > > > Michal Hocko > > > SUSE Labs > > > > > > > Best Regards > Oscar Salvador >
On Fri, 15 Jun 2018 10:00:00 -0400 Pavel Tatashin <pasha.tatashin@oracle.com> wrote: > > > Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > > > Tested-by: Oscar Salvador <osalvador@suse.de> > > > > OK, this makes sense to me. It is definitely much better than the > > original attempt. > > > > Unless I am missing something this should be correct > > Acked-by: Michal Hocko <mhocko@suse.com> > > First of all thank you Naoya for finding and root causing this issue. > > So, with this fix we reserve any hole and !E820_TYPE_RAM or > !E820_TYPE_RESERVED_KERN in e820. I think, this will work because we > do pfn_valid() check in zero_resv_unavail(), so the ranges that do not have > backing struct pages will be skipped. But, I am worried on the performance > implications of when the holes of invalid memory are rather large. We would > have to loop through it in zero_resv_unavail() one pfn at a time. > > Therefore, we might also need to optimize zero_resv_unavail() a little like > this: > > 6407 if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) > 6408 continue; > > Add before "continue": > pfn = ALIGN_DOWN(pfn, pageblock_nr_pages) + pageblock_nr_pageas - 1. > At least, this way, we would skip a section of invalid memory at a time. > > For the patch above: > Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com> > > But, I think the 2nd patch with the optimization above should go along this > this fix. So I expect this patch needs a cc:stable, which I'll add. The optimiation patch seems less important and I'd like to hold that off for 4.19-rc1?
> So I expect this patch needs a cc:stable, which I'll add. Yes. > The optimiation patch seems less important and I'd like to hold that > off for 4.19-rc1? I agree, the optimization is not as important, and can wait for 4.19.
> So I expect this patch needs a cc:stable, which I'll add. > > The optimiation patch seems less important and I'd like to hold that > off for 4.19-rc1? Hi Andrew, Should I resend the optimization patch [1] once 4.18 is released, or will you include it, and I do not need to do anything? [1] http://lkml.kernel.org/r/20180615155733.1175-1-pasha.tatashin@oracle.com Thank you, Pavel
On Mon, 2 Jul 2018 16:05:04 -0400 Pavel Tatashin <pasha.tatashin@oracle.com> wrote: > > So I expect this patch needs a cc:stable, which I'll add. > > > > The optimiation patch seems less important and I'd like to hold that > > off for 4.19-rc1? > > Hi Andrew, > > Should I resend the optimization patch [1] once 4.18 is released, or > will you include it, and I do not need to do anything? > > [1] http://lkml.kernel.org/r/20180615155733.1175-1-pasha.tatashin@oracle.com > http://ozlabs.org/~akpm/mmots/broken-out/mm-skip-invalid-pages-block-at-a-time-in-zero_resv_unresv.patch has been in -mm since Jun 18, so all is well.
> http://ozlabs.org/~akpm/mmots/broken-out/mm-skip-invalid-pages-block-at-a-time-in-zero_resv_unresv.patch > has been in -mm since Jun 18, so all is well. Ah missed it. Thank you. Pavel
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index d1f25c831447..c88c23c658c1 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 addr = 0; /* * The bootstrap memblock region count maximum is 128 entries @@ -1264,13 +1265,21 @@ void __init e820__memblock_setup(void) 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; + /* + * all !E820_TYPE_RAM ranges (including gap ranges) 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 && 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); } /* Throw away partial pages: */