Hugh Dickins 32cc0b7c9d powerpc: add pte_free_defer() for pgtables sharing page
Add powerpc-specific pte_free_defer(), to free table page via call_rcu(). 
pte_free_defer() will be called inside khugepaged's retract_page_tables()
loop, where allocating extra memory cannot be relied upon.  This precedes
the generic version to avoid build breakage from incompatible pgtable_t.

This is awkward because the struct page contains only one rcu_head, but
that page may be shared between PTE_FRAG_NR pagetables, each wanting to
use the rcu_head at the same time.  But powerpc never reuses a fragment
once it has been freed: so mark the page Active in pte_free_defer(),
before calling pte_fragment_free() directly; and there call_rcu() to
pte_free_now() when last fragment is freed and the page is PageActive.

Link: https://lkml.kernel.org/r/6e3ca5f1-334d-4b14-b92d-fc8e99914fcb@google.com
Suggested-by: Jason Gunthorpe <jgg@ziepe.ca>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-08-18 10:12:23 -07:00

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2.2 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_POWERPC_PGALLOC_H
#define _ASM_POWERPC_PGALLOC_H
#include <linux/mm.h>
#ifndef MODULE
static inline gfp_t pgtable_gfp_flags(struct mm_struct *mm, gfp_t gfp)
{
if (unlikely(mm == &init_mm))
return gfp;
return gfp | __GFP_ACCOUNT;
}
#else /* !MODULE */
static inline gfp_t pgtable_gfp_flags(struct mm_struct *mm, gfp_t gfp)
{
return gfp | __GFP_ACCOUNT;
}
#endif /* MODULE */
#define PGALLOC_GFP (GFP_KERNEL | __GFP_ZERO)
pte_t *pte_fragment_alloc(struct mm_struct *mm, int kernel);
static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
{
return (pte_t *)pte_fragment_alloc(mm, 1);
}
static inline pgtable_t pte_alloc_one(struct mm_struct *mm)
{
return (pgtable_t)pte_fragment_alloc(mm, 0);
}
void pte_frag_destroy(void *pte_frag);
void pte_fragment_free(unsigned long *table, int kernel);
static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
{
pte_fragment_free((unsigned long *)pte, 1);
}
static inline void pte_free(struct mm_struct *mm, pgtable_t ptepage)
{
pte_fragment_free((unsigned long *)ptepage, 0);
}
/* arch use pte_free_defer() implementation in arch/powerpc/mm/pgtable-frag.c */
#define pte_free_defer pte_free_defer
void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable);
/*
* Functions that deal with pagetables that could be at any level of
* the table need to be passed an "index_size" so they know how to
* handle allocation. For PTE pages, the allocation size will be
* (2^index_size * sizeof(pointer)) and allocations are drawn from
* the kmem_cache in PGT_CACHE(index_size).
*
* The maximum index size needs to be big enough to allow any
* pagetable sizes we need, but small enough to fit in the low bits of
* any page table pointer. In other words all pagetables, even tiny
* ones, must be aligned to allow at least enough low 0 bits to
* contain this value. This value is also used as a mask, so it must
* be one less than a power of two.
*/
#define MAX_PGTABLE_INDEX_SIZE 0xf
extern struct kmem_cache *pgtable_cache[];
#define PGT_CACHE(shift) pgtable_cache[shift]
#ifdef CONFIG_PPC_BOOK3S
#include <asm/book3s/pgalloc.h>
#else
#include <asm/nohash/pgalloc.h>
#endif
#endif /* _ASM_POWERPC_PGALLOC_H */