mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-05 18:14:07 +08:00
f5678e7f2a
Switch the function documentation to kerneldoc comments, and add WARN_ON_ONCE asserts that the calling thread is a kernel thread and does not have ->mm set (or has ->mm set in the case of unuse_mm). Also give the functions a kthread_ prefix to better document the use case. [hch@lst.de: fix a comment typo, cover the newly merged use_mm/unuse_mm caller in vfio] Link: http://lkml.kernel.org/r/20200416053158.586887-3-hch@lst.de [sfr@canb.auug.org.au: powerpc/vas: fix up for {un}use_mm() rename] Link: http://lkml.kernel.org/r/20200422163935.5aa93ba5@canb.auug.org.au Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Jens Axboe <axboe@kernel.dk> Reviewed-by: Jens Axboe <axboe@kernel.dk> Acked-by: Felix Kuehling <Felix.Kuehling@amd.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [usb] Acked-by: Haren Myneni <haren@linux.ibm.com> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Felipe Balbi <balbi@kernel.org> Cc: Jason Wang <jasowang@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Zhenyu Wang <zhenyuw@linux.intel.com> Cc: Zhi Wang <zhi.a.wang@intel.com> Link: http://lkml.kernel.org/r/20200404094101.672954-6-hch@lst.de Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
118 lines
2.7 KiB
C
118 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Copyright (C) 2014 Davidlohr Bueso.
|
|
*/
|
|
#include <linux/sched/signal.h>
|
|
#include <linux/sched/task.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/vmacache.h>
|
|
|
|
/*
|
|
* Hash based on the pmd of addr if configured with MMU, which provides a good
|
|
* hit rate for workloads with spatial locality. Otherwise, use pages.
|
|
*/
|
|
#ifdef CONFIG_MMU
|
|
#define VMACACHE_SHIFT PMD_SHIFT
|
|
#else
|
|
#define VMACACHE_SHIFT PAGE_SHIFT
|
|
#endif
|
|
#define VMACACHE_HASH(addr) ((addr >> VMACACHE_SHIFT) & VMACACHE_MASK)
|
|
|
|
/*
|
|
* This task may be accessing a foreign mm via (for example)
|
|
* get_user_pages()->find_vma(). The vmacache is task-local and this
|
|
* task's vmacache pertains to a different mm (ie, its own). There is
|
|
* nothing we can do here.
|
|
*
|
|
* Also handle the case where a kernel thread has adopted this mm via
|
|
* kthread_use_mm(). That kernel thread's vmacache is not applicable to this mm.
|
|
*/
|
|
static inline bool vmacache_valid_mm(struct mm_struct *mm)
|
|
{
|
|
return current->mm == mm && !(current->flags & PF_KTHREAD);
|
|
}
|
|
|
|
void vmacache_update(unsigned long addr, struct vm_area_struct *newvma)
|
|
{
|
|
if (vmacache_valid_mm(newvma->vm_mm))
|
|
current->vmacache.vmas[VMACACHE_HASH(addr)] = newvma;
|
|
}
|
|
|
|
static bool vmacache_valid(struct mm_struct *mm)
|
|
{
|
|
struct task_struct *curr;
|
|
|
|
if (!vmacache_valid_mm(mm))
|
|
return false;
|
|
|
|
curr = current;
|
|
if (mm->vmacache_seqnum != curr->vmacache.seqnum) {
|
|
/*
|
|
* First attempt will always be invalid, initialize
|
|
* the new cache for this task here.
|
|
*/
|
|
curr->vmacache.seqnum = mm->vmacache_seqnum;
|
|
vmacache_flush(curr);
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
int idx = VMACACHE_HASH(addr);
|
|
int i;
|
|
|
|
count_vm_vmacache_event(VMACACHE_FIND_CALLS);
|
|
|
|
if (!vmacache_valid(mm))
|
|
return NULL;
|
|
|
|
for (i = 0; i < VMACACHE_SIZE; i++) {
|
|
struct vm_area_struct *vma = current->vmacache.vmas[idx];
|
|
|
|
if (vma) {
|
|
#ifdef CONFIG_DEBUG_VM_VMACACHE
|
|
if (WARN_ON_ONCE(vma->vm_mm != mm))
|
|
break;
|
|
#endif
|
|
if (vma->vm_start <= addr && vma->vm_end > addr) {
|
|
count_vm_vmacache_event(VMACACHE_FIND_HITS);
|
|
return vma;
|
|
}
|
|
}
|
|
if (++idx == VMACACHE_SIZE)
|
|
idx = 0;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
#ifndef CONFIG_MMU
|
|
struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm,
|
|
unsigned long start,
|
|
unsigned long end)
|
|
{
|
|
int idx = VMACACHE_HASH(start);
|
|
int i;
|
|
|
|
count_vm_vmacache_event(VMACACHE_FIND_CALLS);
|
|
|
|
if (!vmacache_valid(mm))
|
|
return NULL;
|
|
|
|
for (i = 0; i < VMACACHE_SIZE; i++) {
|
|
struct vm_area_struct *vma = current->vmacache.vmas[idx];
|
|
|
|
if (vma && vma->vm_start == start && vma->vm_end == end) {
|
|
count_vm_vmacache_event(VMACACHE_FIND_HITS);
|
|
return vma;
|
|
}
|
|
if (++idx == VMACACHE_SIZE)
|
|
idx = 0;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
#endif
|