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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-24 00:00:52 +07:00
mm: remove the now-unnecessary mmget_still_valid() hack
The preceding patches have ensured that core dumping properly takes the mmap_lock. Thanks to that, we can now remove mmget_still_valid() and all its users. Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Hugh Dickins <hughd@google.com> Link: http://lkml.kernel.org/r/20200827114932.3572699-8-jannh@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -845,8 +845,6 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
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* will only be one mm, so no big deal.
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*/
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mmap_read_lock(mm);
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if (!mmget_still_valid(mm))
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goto skip_mm;
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mutex_lock(&ufile->umap_lock);
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list_for_each_entry_safe (priv, next_priv, &ufile->umaps,
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list) {
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@ -865,7 +863,6 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
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}
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}
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mutex_unlock(&ufile->umap_lock);
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skip_mm:
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mmap_read_unlock(mm);
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mmput(mm);
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}
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@ -1480,31 +1480,29 @@ static int vfio_pci_zap_and_vma_lock(struct vfio_pci_device *vdev, bool try)
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} else {
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mmap_read_lock(mm);
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}
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if (mmget_still_valid(mm)) {
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if (try) {
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if (!mutex_trylock(&vdev->vma_lock)) {
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mmap_read_unlock(mm);
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mmput(mm);
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return 0;
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}
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} else {
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mutex_lock(&vdev->vma_lock);
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if (try) {
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if (!mutex_trylock(&vdev->vma_lock)) {
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mmap_read_unlock(mm);
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mmput(mm);
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return 0;
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}
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list_for_each_entry_safe(mmap_vma, tmp,
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&vdev->vma_list, vma_next) {
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struct vm_area_struct *vma = mmap_vma->vma;
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if (vma->vm_mm != mm)
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continue;
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list_del(&mmap_vma->vma_next);
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kfree(mmap_vma);
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zap_vma_ptes(vma, vma->vm_start,
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vma->vm_end - vma->vm_start);
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}
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mutex_unlock(&vdev->vma_lock);
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} else {
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mutex_lock(&vdev->vma_lock);
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}
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list_for_each_entry_safe(mmap_vma, tmp,
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&vdev->vma_list, vma_next) {
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struct vm_area_struct *vma = mmap_vma->vma;
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if (vma->vm_mm != mm)
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continue;
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list_del(&mmap_vma->vma_next);
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kfree(mmap_vma);
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zap_vma_ptes(vma, vma->vm_start,
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vma->vm_end - vma->vm_start);
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}
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mutex_unlock(&vdev->vma_lock);
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mmap_read_unlock(mm);
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mmput(mm);
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}
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@ -1244,24 +1244,6 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
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count = -EINTR;
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goto out_mm;
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}
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/*
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* Avoid to modify vma->vm_flags
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* without locked ops while the
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* coredump reads the vm_flags.
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*/
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if (!mmget_still_valid(mm)) {
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/*
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* Silently return "count"
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* like if get_task_mm()
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* failed. FIXME: should this
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* function have returned
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* -ESRCH if get_task_mm()
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* failed like if
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* get_proc_task() fails?
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*/
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mmap_write_unlock(mm);
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goto out_mm;
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}
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for (vma = mm->mmap; vma; vma = vma->vm_next) {
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vma->vm_flags &= ~VM_SOFTDIRTY;
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vma_set_page_prot(vma);
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@ -601,8 +601,6 @@ static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
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/* the various vma->vm_userfaultfd_ctx still points to it */
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mmap_write_lock(mm);
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/* no task can run (and in turn coredump) yet */
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VM_WARN_ON(!mmget_still_valid(mm));
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for (vma = mm->mmap; vma; vma = vma->vm_next)
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if (vma->vm_userfaultfd_ctx.ctx == release_new_ctx) {
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vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
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@ -842,7 +840,6 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
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/* len == 0 means wake all */
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struct userfaultfd_wake_range range = { .len = 0, };
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unsigned long new_flags;
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bool still_valid;
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WRITE_ONCE(ctx->released, true);
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@ -858,7 +855,6 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
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* taking the mmap_lock for writing.
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*/
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mmap_write_lock(mm);
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still_valid = mmget_still_valid(mm);
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prev = NULL;
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for (vma = mm->mmap; vma; vma = vma->vm_next) {
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cond_resched();
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@ -869,17 +865,15 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
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continue;
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}
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new_flags = vma->vm_flags & ~(VM_UFFD_MISSING | VM_UFFD_WP);
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if (still_valid) {
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prev = vma_merge(mm, prev, vma->vm_start, vma->vm_end,
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new_flags, vma->anon_vma,
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vma->vm_file, vma->vm_pgoff,
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vma_policy(vma),
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NULL_VM_UFFD_CTX);
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if (prev)
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vma = prev;
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else
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prev = vma;
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}
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prev = vma_merge(mm, prev, vma->vm_start, vma->vm_end,
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new_flags, vma->anon_vma,
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vma->vm_file, vma->vm_pgoff,
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vma_policy(vma),
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NULL_VM_UFFD_CTX);
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if (prev)
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vma = prev;
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else
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prev = vma;
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vma->vm_flags = new_flags;
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vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
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}
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@ -1309,8 +1303,6 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
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goto out;
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mmap_write_lock(mm);
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if (!mmget_still_valid(mm))
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goto out_unlock;
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vma = find_vma_prev(mm, start, &prev);
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if (!vma)
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goto out_unlock;
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@ -1511,8 +1503,6 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
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goto out;
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mmap_write_lock(mm);
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if (!mmget_still_valid(mm))
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goto out_unlock;
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vma = find_vma_prev(mm, start, &prev);
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if (!vma)
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goto out_unlock;
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@ -49,31 +49,6 @@ static inline void mmdrop(struct mm_struct *mm)
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__mmdrop(mm);
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}
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/*
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* This has to be called after a get_task_mm()/mmget_not_zero()
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* followed by taking the mmap_lock for writing before modifying the
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* vmas or anything the coredump pretends not to change from under it.
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*
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* It also has to be called when mmgrab() is used in the context of
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* the process, but then the mm_count refcount is transferred outside
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* the context of the process to run down_write() on that pinned mm.
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*
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* NOTE: find_extend_vma() called from GUP context is the only place
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* that can modify the "mm" (notably the vm_start/end) under mmap_lock
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* for reading and outside the context of the process, so it is also
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* the only case that holds the mmap_lock for reading that must call
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* this function. Generally if the mmap_lock is hold for reading
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* there's no need of this check after get_task_mm()/mmget_not_zero().
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*
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* This function can be obsoleted and the check can be removed, after
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* the coredump code will hold the mmap_lock for writing before
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* invoking the ->core_dump methods.
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*/
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static inline bool mmget_still_valid(struct mm_struct *mm)
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{
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return likely(!mm->core_state);
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}
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/**
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* mmget() - Pin the address space associated with a &struct mm_struct.
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* @mm: The address space to pin.
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@ -434,7 +434,7 @@ static void insert_to_mm_slots_hash(struct mm_struct *mm,
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static inline int khugepaged_test_exit(struct mm_struct *mm)
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{
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return atomic_read(&mm->mm_users) == 0 || !mmget_still_valid(mm);
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return atomic_read(&mm->mm_users) == 0;
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}
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static bool hugepage_vma_check(struct vm_area_struct *vma,
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17
mm/madvise.c
17
mm/madvise.c
@ -1085,23 +1085,6 @@ int do_madvise(unsigned long start, size_t len_in, int behavior)
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if (write) {
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if (mmap_write_lock_killable(current->mm))
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return -EINTR;
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/*
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* We may have stolen the mm from another process
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* that is undergoing core dumping.
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*
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* Right now that's io_ring, in the future it may
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* be remote process management and not "current"
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* at all.
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*
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* We need to fix core dumping to not do this,
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* but for now we have the mmget_still_valid()
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* model.
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*/
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if (!mmget_still_valid(current->mm)) {
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mmap_write_unlock(current->mm);
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return -EINTR;
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}
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} else {
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mmap_read_lock(current->mm);
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}
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@ -2562,7 +2562,7 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr)
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if (vma && (vma->vm_start <= addr))
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return vma;
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/* don't alter vm_end if the coredump is running */
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if (!prev || !mmget_still_valid(mm) || expand_stack(prev, addr))
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if (!prev || expand_stack(prev, addr))
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return NULL;
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if (prev->vm_flags & VM_LOCKED)
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populate_vma_page_range(prev, addr, prev->vm_end, NULL);
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@ -2588,9 +2588,6 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr)
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return vma;
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if (!(vma->vm_flags & VM_GROWSDOWN))
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return NULL;
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/* don't alter vm_start if the coredump is running */
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if (!mmget_still_valid(mm))
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return NULL;
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start = vma->vm_start;
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if (expand_stack(vma, addr))
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return NULL;
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