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![Christoph Hellwig](/assets/img/avatar_default.png)
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>
117 lines
2.7 KiB
C
117 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2014 Davidlohr Bueso.
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*/
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#include <linux/sched/signal.h>
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#include <linux/sched/task.h>
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#include <linux/mm.h>
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#include <linux/vmacache.h>
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/*
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* Hash based on the pmd of addr if configured with MMU, which provides a good
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* hit rate for workloads with spatial locality. Otherwise, use pages.
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*/
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#ifdef CONFIG_MMU
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#define VMACACHE_SHIFT PMD_SHIFT
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#else
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#define VMACACHE_SHIFT PAGE_SHIFT
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#endif
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#define VMACACHE_HASH(addr) ((addr >> VMACACHE_SHIFT) & VMACACHE_MASK)
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/*
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* This task may be accessing a foreign mm via (for example)
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* get_user_pages()->find_vma(). The vmacache is task-local and this
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* task's vmacache pertains to a different mm (ie, its own). There is
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* nothing we can do here.
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*
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* Also handle the case where a kernel thread has adopted this mm via
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* kthread_use_mm(). That kernel thread's vmacache is not applicable to this mm.
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*/
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static inline bool vmacache_valid_mm(struct mm_struct *mm)
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{
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return current->mm == mm && !(current->flags & PF_KTHREAD);
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}
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void vmacache_update(unsigned long addr, struct vm_area_struct *newvma)
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{
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if (vmacache_valid_mm(newvma->vm_mm))
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current->vmacache.vmas[VMACACHE_HASH(addr)] = newvma;
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}
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static bool vmacache_valid(struct mm_struct *mm)
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{
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struct task_struct *curr;
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if (!vmacache_valid_mm(mm))
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return false;
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curr = current;
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if (mm->vmacache_seqnum != curr->vmacache.seqnum) {
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/*
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* First attempt will always be invalid, initialize
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* the new cache for this task here.
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*/
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curr->vmacache.seqnum = mm->vmacache_seqnum;
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vmacache_flush(curr);
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return false;
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}
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return true;
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}
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struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr)
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{
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int idx = VMACACHE_HASH(addr);
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int i;
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count_vm_vmacache_event(VMACACHE_FIND_CALLS);
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if (!vmacache_valid(mm))
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return NULL;
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for (i = 0; i < VMACACHE_SIZE; i++) {
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struct vm_area_struct *vma = current->vmacache.vmas[idx];
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if (vma) {
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#ifdef CONFIG_DEBUG_VM_VMACACHE
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if (WARN_ON_ONCE(vma->vm_mm != mm))
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break;
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#endif
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if (vma->vm_start <= addr && vma->vm_end > addr) {
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count_vm_vmacache_event(VMACACHE_FIND_HITS);
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return vma;
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}
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}
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if (++idx == VMACACHE_SIZE)
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idx = 0;
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}
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return NULL;
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}
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#ifndef CONFIG_MMU
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struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm,
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unsigned long start,
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unsigned long end)
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{
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int idx = VMACACHE_HASH(start);
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int i;
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count_vm_vmacache_event(VMACACHE_FIND_CALLS);
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if (!vmacache_valid(mm))
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return NULL;
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for (i = 0; i < VMACACHE_SIZE; i++) {
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struct vm_area_struct *vma = current->vmacache.vmas[idx];
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if (vma && vma->vm_start == start && vma->vm_end == end) {
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count_vm_vmacache_event(VMACACHE_FIND_HITS);
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return vma;
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}
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if (++idx == VMACACHE_SIZE)
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idx = 0;
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}
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return NULL;
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}
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#endif
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