Files
Nadav Amit b0313bc7f5 hugetlbfs: flush TLBs correctly after huge_pmd_unshare
commit a4a118f2eead1d6c49e00765de89878288d4b890 upstream.

When __unmap_hugepage_range() calls to huge_pmd_unshare() succeed, a TLB
flush is missing.  This TLB flush must be performed before releasing the
i_mmap_rwsem, in order to prevent an unshared PMDs page from being
released and reused before the TLB flush took place.

Arguably, a comprehensive solution would use mmu_gather interface to
batch the TLB flushes and the PMDs page release, however it is not an
easy solution: (1) try_to_unmap_one() and try_to_migrate_one() also call
huge_pmd_unshare() and they cannot use the mmu_gather interface; and (2)
deferring the release of the page reference for the PMDs page until
after i_mmap_rwsem is dropeed can confuse huge_pmd_unshare() into
thinking PMDs are shared when they are not.

Fix __unmap_hugepage_range() by adding the missing TLB flush, and
forcing a flush when unshare is successful.

Fixes: 24669e5847 ("hugetlb: use mmu_gather instead of a temporary linked list for accumulating pages)" # 3.6
Signed-off-by: Nadav Amit <namit@vmware.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-12-01 09:27:43 +01:00

180 lines
4.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_SH_TLB_H
#define __ASM_SH_TLB_H
#ifdef CONFIG_SUPERH64
# include <asm/tlb_64.h>
#endif
#ifndef __ASSEMBLY__
#include <linux/pagemap.h>
#ifdef CONFIG_MMU
#include <linux/swap.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
/*
* TLB handling. This allows us to remove pages from the page
* tables, and efficiently handle the TLB issues.
*/
struct mmu_gather {
struct mm_struct *mm;
unsigned int fullmm;
unsigned long start, end;
};
static inline void init_tlb_gather(struct mmu_gather *tlb)
{
tlb->start = TASK_SIZE;
tlb->end = 0;
if (tlb->fullmm) {
tlb->start = 0;
tlb->end = TASK_SIZE;
}
}
static inline void
arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
unsigned long start, unsigned long end)
{
tlb->mm = mm;
tlb->start = start;
tlb->end = end;
tlb->fullmm = !(start | (end+1));
init_tlb_gather(tlb);
}
static inline void
arch_tlb_finish_mmu(struct mmu_gather *tlb,
unsigned long start, unsigned long end, bool force)
{
if (tlb->fullmm || force)
flush_tlb_mm(tlb->mm);
/* keep the page table cache within bounds */
check_pgt_cache();
}
static inline void
tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long address)
{
if (tlb->start > address)
tlb->start = address;
if (tlb->end < address + PAGE_SIZE)
tlb->end = address + PAGE_SIZE;
}
#define tlb_remove_huge_tlb_entry(h, tlb, ptep, address) \
tlb_remove_tlb_entry(tlb, ptep, address)
/*
* In the case of tlb vma handling, we can optimise these away in the
* case where we're doing a full MM flush. When we're doing a munmap,
* the vmas are adjusted to only cover the region to be torn down.
*/
static inline void
tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
{
if (!tlb->fullmm)
flush_cache_range(vma, vma->vm_start, vma->vm_end);
}
static inline void
tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
{
if (!tlb->fullmm && tlb->end) {
flush_tlb_range(vma, tlb->start, tlb->end);
init_tlb_gather(tlb);
}
}
static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
{
}
static inline void tlb_flush_mmu_free(struct mmu_gather *tlb)
{
}
static inline void tlb_flush_mmu(struct mmu_gather *tlb)
{
}
static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
{
free_page_and_swap_cache(page);
return false; /* avoid calling tlb_flush_mmu */
}
static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
{
__tlb_remove_page(tlb, page);
}
static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
struct page *page, int page_size)
{
return __tlb_remove_page(tlb, page);
}
static inline void tlb_remove_page_size(struct mmu_gather *tlb,
struct page *page, int page_size)
{
return tlb_remove_page(tlb, page);
}
static inline void
tlb_flush_pmd_range(struct mmu_gather *tlb, unsigned long address,
unsigned long size)
{
if (tlb->start > address)
tlb->start = address;
if (tlb->end < address + size)
tlb->end = address + size;
}
#define tlb_remove_check_page_size_change tlb_remove_check_page_size_change
static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
unsigned int page_size)
{
}
#define pte_free_tlb(tlb, ptep, addr) pte_free((tlb)->mm, ptep)
#define pmd_free_tlb(tlb, pmdp, addr) pmd_free((tlb)->mm, pmdp)
#define pud_free_tlb(tlb, pudp, addr) pud_free((tlb)->mm, pudp)
#define tlb_migrate_finish(mm) do { } while (0)
#if defined(CONFIG_CPU_SH4) || defined(CONFIG_SUPERH64)
extern void tlb_wire_entry(struct vm_area_struct *, unsigned long, pte_t);
extern void tlb_unwire_entry(void);
#else
static inline void tlb_wire_entry(struct vm_area_struct *vma ,
unsigned long addr, pte_t pte)
{
BUG();
}
static inline void tlb_unwire_entry(void)
{
BUG();
}
#endif
#else /* CONFIG_MMU */
#define tlb_start_vma(tlb, vma) do { } while (0)
#define tlb_end_vma(tlb, vma) do { } while (0)
#define __tlb_remove_tlb_entry(tlb, pte, address) do { } while (0)
#define tlb_flush(tlb) do { } while (0)
#include <asm-generic/tlb.h>
#endif /* CONFIG_MMU */
#endif /* __ASSEMBLY__ */
#endif /* __ASM_SH_TLB_H */