talos-op-linux/arch/powerpc/include/asm/pgalloc-64.h, branch v4.4.4

powerpc: Fix PTE page address mismatch in pgtable ctor/dtor

2013-12-10T00:25:05+00:00

In pte_alloc_one(), pgtable_page_ctor() is passed an address that has not been converted by page_address() to the newly allocated PTE page. When the PTE is freed, __pte_free_tlb() calls pgtable_page_dtor() with an address to the PTE page that has been converted by page_address(). The mismatch in the PTE's page address causes pgtable_page_dtor() to access invalid memory, so resources for that PTE (such as the page lock) is not properly cleaned up. On PPC32, only SMP kernels are affected. On PPC64, only SMP kernels with 4K page size are affected. This bug was introduced by commit d614bb041209fd7cb5e4b35e11a7b2f6ee8f62b8 "powerpc: Move the pte free routines from common header". On a preempt-rt kernel, a spinlock is dynamically allocated for each PTE in pgtable_page_ctor(). When the PTE is freed, calling pgtable_page_dtor() with a mismatched page address causes a memory leak, as the pointer to the PTE's spinlock is bogus. On mainline, there isn't any immediately obvious symptoms, but the problem still exists here. Fixes: d614bb041209fd7c "powerpc: Move the pte free routes from common header" Cc: Paul Mackerras Cc: Aneesh Kumar K.V Cc: Benjamin Herrenschmidt Cc: linux-stable # v3.10+ Signed-off-by: Hong H. Pham Reviewed-by: Aneesh Kumar K.V Signed-off-by: Benjamin Herrenschmidt

powerpc/kdump: Adding symbols in vmcoreinfo to facilitate dump filtering

2013-11-25T00:50:12+00:00

When CONFIG_SPARSEMEM_VMEMMAP option is used in kernel, makedumpfile fails to filter vmcore dump as it fails to do vmemmap translations. So far dump filtering on ppc64 never had to deal with vmemmap addresses seperately as vmemmap regions where mapped in zone normal. But with the inclusion of CONFIG_SPARSEMEM_VMEMMAP config option in kernel, this vmemmap address translation support becomes necessary for dump filtering. For vmemmap adress translation, few kernel symbols are needed by dump filtering tool. This patch adds those symbols to vmcoreinfo, which a dump filtering tool can use for filtering the kernel dump. Tested this changes successfully with makedumpfile tool that supports vmemmap to physical address translation outside zone normal. [ Removed unneeded #ifdef as suggested by Michael Ellerman --BenH ] Signed-off-by: Hari Bathini Signed-off-by: Benjamin Herrenschmidt

powerpc: handle pgtable_page_ctor() fail

2013-11-15T00:32:18+00:00

Signed-off-by: Kirill A. Shutemov Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

powerpc/THP: Double the PMD table size for THP

2013-06-21T06:01:53+00:00

THP code does PTE page allocation along with large page request and deposit them for later use. This is to ensure that we won't have any failures when we split hugepages to regular pages. On powerpc we want to use the deposited PTE page for storing hash pte slot and secondary bit information for the HPTEs. We use the second half of the pmd table to save the deposted PTE page. Reviewed-by: David Gibson Signed-off-by: Aneesh Kumar K.V Signed-off-by: Benjamin Herrenschmidt

powerpc/mm: Use the correct mask value when looking at pgtable address

2013-05-14T04:36:17+00:00

Our pgtable are 2*sizeof(pte_t)*PTRS_PER_PTE which is PTE_FRAG_SIZE. Instead of depending on frag size, mask with PMD_MASKED_BITS. Signed-off-by: Aneesh Kumar K.V Signed-off-by: Benjamin Herrenschmidt

powerpc: Reduce PTE table memory wastage

2013-04-30T06:00:07+00:00

We allocate one page for the last level of linux page table. With THP and large page size of 16MB, that would mean we are wasting large part of that page. To map 16MB area, we only need a PTE space of 2K with 64K page size. This patch reduce the space wastage by sharing the page allocated for the last level of linux page table with multiple pmd entries. We call these smaller chunks PTE page fragments and allocated page, PTE page. In order to support systems which doesn't have 64K HPTE support, we also add another 2K to PTE page fragment. The second half of the PTE fragments is used for storing slot and secondary bit information of an HPTE. With this we now have a 4K PTE fragment. We use a simple approach to share the PTE page. On allocation, we bump the PTE page refcount to 16 and share the PTE page with the next 16 pte alloc request. This should help in the node locality of the PTE page fragment, assuming that the immediate pte alloc request will mostly come from the same NUMA node. We don't try to reuse the freed PTE page fragment. Hence we could be waisting some space. Signed-off-by: Aneesh Kumar K.V Acked-by: Paul Mackerras Signed-off-by: Benjamin Herrenschmidt

powerpc: Move the pte free routines from common header

2013-04-30T06:00:04+00:00

Acked-by: Paul Mackerras This patch moves the common code to 32/64 bit headers and also duplicate 4K_PAGES and 64K_PAGES section. We will later change the 64 bit 64K_PAGES version to support smaller PTE fragments. The patch doesn't introduce any functional changes. Acked-by: Paul Mackerras Signed-off-by: Aneesh Kumar K.V Signed-off-by: Benjamin Herrenschmidt

powerpc: New hugepage directory format

2013-04-30T05:59:53+00:00

Change the hugepage directory format so that we can have leaf ptes directly at page directory avoiding the allocation of hugepage directory. With the new table format we have 3 cases for pgds and pmds: (1) invalid (all zeroes) (2) pointer to next table, as normal; bottom 6 bits == 0 (4) hugepd pointer, bottom two bits == 00, next 4 bits indicate size of table Instead of storing shift value in hugepd pointer we use mmu_psize_def index so that we can fit all the supported hugepage size in 4 bits Signed-off-by: Aneesh Kumar K.V Acked-by: Paul Mackerras Signed-off-by: Benjamin Herrenschmidt

powerpc/mm: Track backing pages allocated by vmemmap_populate()

2010-05-06T06:49:27+00:00

We need to keep track of the backing pages that get allocated by vmemmap_populate() so that when we use kdump, the dump-capture kernel knows where these pages are. We use a simple linked list of structures that contain the physical address of the backing page and corresponding virtual address to track the backing pages. To save space, we just use a pointer to the next struct vmemmap_backing. We can also do this because we never remove nodes. We call the pointer "list" to be compatible with changes made to the crash utility. vmemmap_populate() is called either at boot-time or on a memory hotplug operation. We don't have to worry about the boot-time calls because they will be inherently single-threaded, and for a memory hotplug operation vmemmap_populate() is called through: sparse_add_one_section() | V kmalloc_section_memmap() | V sparse_mem_map_populate() | V vmemmap_populate() and in sparse_add_one_section() we're protected by pgdat_resize_lock(). So, we don't need a spinlock to protect the vmemmap_list. We allocate space for the vmemmap_backing structs by allocating whole pages in vmemmap_list_alloc() and then handing out chunks of this to vmemmap_list_populate(). This means that we waste at most just under one page, but this keeps the code is simple. Signed-off-by: Mark Nelson Signed-off-by: Benjamin Herrenschmidt

powerpc/mm: Fix pgtable cache cleanup with CONFIG_PPC_SUBPAGE_PROT

2009-12-08T04:59:33+00:00

Commit a0668cdc154e54bf0c85182e0535eea237d53146 cleans up the handling of kmem_caches for allocating various levels of pagetables. Unfortunately, it conflicts badly with CONFIG_PPC_SUBPAGE_PROT, due to the latter's cleverly hidden technique of adding some extra allocation space to the top level page directory to store the extra information it needs. Since that extra allocation really doesn't fit into the cleaned up page directory allocating scheme, this patch alters CONFIG_PPC_SUBPAGE_PROT to instead allocate its struct subpage_prot_table as part of the mm_context_t. Signed-off-by: David Gibson Signed-off-by: Benjamin Herrenschmidt