| From 36ddb1757ef1943ac751efe676c7d879a857e238 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Fri, 26 Oct 2018 15:10:15 -0700 |
| Subject: mm: zero remaining unavailable struct pages |
| |
| From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> |
| |
| [ Upstream commit 907ec5fca3dc38d37737de826f06f25b063aa08e ] |
| |
| Patch series "mm: Fix for movable_node boot option", v3. |
| |
| This patch series contains a fix for the movable_node boot option issue |
| which was introduced by commit 124049decbb1 ("x86/e820: put !E820_TYPE_RAM |
| regions into memblock.reserved"). |
| |
| The commit breaks the option because it changed the memory gap range to |
| reserved memblock. So, the node is marked as Normal zone even if the SRAT |
| has Hot pluggable affinity. |
| |
| First and second patch fix the original issue which the commit tried to |
| fix, then revert the commit. |
| |
| This patch (of 3): |
| |
| 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 |
| outside memblock.memory, but currently it covers only the reserved |
| unavailable range (i.e. memblock.memory && !memblock.reserved). This |
| patch extends it to cover all unavailable range, which fixes the reported |
| issue. |
| |
| Link: http://lkml.kernel.org/r/20181002143821.5112-2-msys.mizuma@gmail.com |
| Fixes: f7f99100d8d9 ("mm: stop zeroing memory during allocation in vmemmap") |
| Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> |
| Signed-off-by-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> |
| Tested-by: Oscar Salvador <osalvador@suse.de> |
| Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> |
| Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com> |
| Cc: Ingo Molnar <mingo@kernel.org> |
| Cc: Michal Hocko <mhocko@kernel.org> |
| Cc: Thomas Gleixner <tglx@linutronix.de> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| include/linux/memblock.h | 15 --------------- |
| mm/page_alloc.c | 36 +++++++++++++++++++++++++----------- |
| 2 files changed, 25 insertions(+), 26 deletions(-) |
| |
| diff --git a/include/linux/memblock.h b/include/linux/memblock.h |
| index 5169205493782..2acdd046df2d5 100644 |
| --- a/include/linux/memblock.h |
| +++ b/include/linux/memblock.h |
| @@ -265,21 +265,6 @@ void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn, |
| for_each_mem_range_rev(i, &memblock.memory, &memblock.reserved, \ |
| nid, flags, p_start, p_end, p_nid) |
| |
| -/** |
| - * for_each_resv_unavail_range - iterate through reserved and unavailable memory |
| - * @i: u64 used as loop variable |
| - * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL |
| - * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL |
| - * |
| - * Walks over unavailable but reserved (reserved && !memory) areas of memblock. |
| - * Available as soon as memblock is initialized. |
| - * Note: because this memory does not belong to any physical node, flags and |
| - * nid arguments do not make sense and thus not exported as arguments. |
| - */ |
| -#define for_each_resv_unavail_range(i, p_start, p_end) \ |
| - for_each_mem_range(i, &memblock.reserved, &memblock.memory, \ |
| - NUMA_NO_NODE, MEMBLOCK_NONE, p_start, p_end, NULL) |
| - |
| static inline void memblock_set_region_flags(struct memblock_region *r, |
| enum memblock_flags flags) |
| { |
| diff --git a/mm/page_alloc.c b/mm/page_alloc.c |
| index 74fb5c338e8fb..19f2e77d1c50b 100644 |
| --- a/mm/page_alloc.c |
| +++ b/mm/page_alloc.c |
| @@ -6462,29 +6462,42 @@ void __init free_area_init_node(int nid, unsigned long *zones_size, |
| * struct pages which are reserved in memblock allocator and their fields |
| * may be accessed (for example page_to_pfn() on some configuration accesses |
| * flags). We must explicitly zero those struct pages. |
| + * |
| + * This function also addresses a similar issue where struct pages are left |
| + * uninitialized because the physical address range is not covered by |
| + * memblock.memory or memblock.reserved. That could happen when memblock |
| + * layout is manually configured via memmap=. |
| */ |
| void __init zero_resv_unavail(void) |
| { |
| phys_addr_t start, end; |
| unsigned long pfn; |
| u64 i, pgcnt; |
| + phys_addr_t next = 0; |
| |
| /* |
| - * Loop through ranges that are reserved, but do not have reported |
| - * physical memory backing. |
| + * Loop through unavailable ranges not covered by memblock.memory. |
| */ |
| pgcnt = 0; |
| - for_each_resv_unavail_range(i, &start, &end) { |
| - for (pfn = PFN_DOWN(start); pfn < PFN_UP(end); pfn++) { |
| - if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) { |
| - pfn = ALIGN_DOWN(pfn, pageblock_nr_pages) |
| - + pageblock_nr_pages - 1; |
| - continue; |
| + for_each_mem_range(i, &memblock.memory, NULL, |
| + NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end, NULL) { |
| + if (next < start) { |
| + for (pfn = PFN_DOWN(next); pfn < PFN_UP(start); pfn++) { |
| + if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) |
| + continue; |
| + mm_zero_struct_page(pfn_to_page(pfn)); |
| + pgcnt++; |
| } |
| - mm_zero_struct_page(pfn_to_page(pfn)); |
| - pgcnt++; |
| } |
| + next = end; |
| } |
| + for (pfn = PFN_DOWN(next); pfn < max_pfn; pfn++) { |
| + if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) |
| + continue; |
| + mm_zero_struct_page(pfn_to_page(pfn)); |
| + pgcnt++; |
| + } |
| + |
| |
| /* |
| * Struct pages that do not have backing memory. This could be because |
| @@ -6494,7 +6507,8 @@ void __init zero_resv_unavail(void) |
| * this code can be removed. |
| */ |
| if (pgcnt) |
| - pr_info("Reserved but unavailable: %lld pages", pgcnt); |
| + pr_info("Zeroed struct page in unavailable ranges: %lld pages", pgcnt); |
| + |
| } |
| #endif /* CONFIG_HAVE_MEMBLOCK && !CONFIG_FLAT_NODE_MEM_MAP */ |
| |
| -- |
| 2.20.1 |
| |