| Message ID | 20241018174114.2871880-3-Liam.Howlett@oracle.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/mremap: Remove extra vma tree walk | expand |
On Fri, Oct 18, 2024 at 01:41:14PM -0400, Liam R. Howlett wrote: > From: "Liam R. Howlett" <Liam.Howlett@Oracle.com> > > mremap_to() has a goto label at the end that doesn't unwind anything. > Removing the label makes the code cleaner. > > This commit also adds documentation on the function. > > Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> This is a nice cleanup, thanks! Other than nits below, LGTM, so: Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> > --- > mm/mremap.c | 46 +++++++++++++++++++++++++++------------------- > 1 file changed, 27 insertions(+), 19 deletions(-) > > diff --git a/mm/mremap.c b/mm/mremap.c > index e781ec4573ca..4c79ab92eb8f 100644 > --- a/mm/mremap.c > +++ b/mm/mremap.c > @@ -887,6 +887,20 @@ static int resize_is_valid(struct vm_area_struct *vma, unsigned long addr, > return 0; > } > > +/* > + * mremap_to() - remap a vma to a new location > + * @addr: The old address > + * @old_len: The old size > + * @new_addr: The target address > + * @new_len: The new size > + * @locked: If the returned vma is locked (VM_LOCKED) > + * @flags: the mremap flags > + * @uf: The mremap userfaultfd context > + * @uf_unmap_early: The userfaultfd unmap early context > + * @uf_unmap: The userfaultfd unmap context Nit - these are lists of userfaultfd_unmap_ctx rather than contexts. But I mean, the naming around this is generally not great and not your fault so not a big deal. > + * > + * Returns: The new address of the vma or an error. > + */ > static unsigned long mremap_to(unsigned long addr, unsigned long old_len, > unsigned long new_addr, unsigned long new_len, bool *locked, > unsigned long flags, struct vm_userfaultfd_ctx *uf, > @@ -895,18 +909,18 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, > { > struct mm_struct *mm = current->mm; > struct vm_area_struct *vma; > - unsigned long ret = -EINVAL; > + unsigned long ret; > unsigned long map_flags = 0; > > if (offset_in_page(new_addr)) > - goto out; > + return -EINVAL; > > if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) > - goto out; > + return -EINVAL; > > /* Ensure the old/new locations do not overlap */ > if (addr + old_len > new_addr && new_addr + new_len > addr) > - goto out; > + return -EINVAL; > > /* > * move_vma() need us to stay 4 maps below the threshold, otherwise > @@ -933,31 +947,28 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, > */ > ret = do_munmap(mm, new_addr, new_len, uf_unmap_early); > if (ret) > - goto out; > + return ret; > } > > if (old_len > new_len) { > ret = do_munmap(mm, addr+new_len, old_len - new_len, uf_unmap); > if (ret) > - goto out; > + return ret; > old_len = new_len; > } > > vma = vma_lookup(mm, addr); > - if (!vma) { > - ret = -EFAULT; > - goto out; > - } > + if (!vma) > + return -EFAULT; > > ret = resize_is_valid(vma, addr, old_len, new_len, flags); > if (ret) > - goto out; > + return ret; > > /* MREMAP_DONTUNMAP expands by old_len since old_len == new_len */ > if (flags & MREMAP_DONTUNMAP && > !may_expand_vm(mm, vma->vm_flags, old_len >> PAGE_SHIFT)) { > - ret = -ENOMEM; > - goto out; > + return -ENOMEM; > } > > if (flags & MREMAP_FIXED) > @@ -970,17 +981,14 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, > ((addr - vma->vm_start) >> PAGE_SHIFT), > map_flags); Unrelated to your change, but I'm really confused as to why we're doing this even if MREMAP_FIXED might be set, then ignore its return value if it is set? Would be way nicer to do something like: if (!(flags & MREMAP_FIXED)) { new_addr = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT), map_flags); if (IS_ERR_VALUE(new_addr)) return new_addr; } Anyway one for another series. I'd say the 'ret' variable is badly named now, but it was badly named before so there's zero delta on that. > if (IS_ERR_VALUE(ret)) > - goto out; > + return ret; > > /* We got a new mapping */ > if (!(flags & MREMAP_FIXED)) > new_addr = ret; > > - ret = move_vma(vma, addr, old_len, new_len, new_addr, locked, flags, uf, > - uf_unmap); > - > -out: > - return ret; > + return move_vma(vma, addr, old_len, new_len, new_addr, locked, flags, > + uf, uf_unmap); > } > > static int vma_expandable(struct vm_area_struct *vma, unsigned long delta) > -- > 2.43.0 >
On Fri, Oct 18, 2024 at 6:41 PM Liam R. Howlett <Liam.Howlett@oracle.com> wrote: > > From: "Liam R. Howlett" <Liam.Howlett@Oracle.com> > > mremap_to() has a goto label at the end that doesn't unwind anything. > Removing the label makes the code cleaner. > > This commit also adds documentation on the function. Thanks for the nice cleanup across this series :) > > Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Reviewed-by: Pedro Falcato <pedro.falcato@gmail.com>
diff --git a/mm/mremap.c b/mm/mremap.c index e781ec4573ca..4c79ab92eb8f 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -887,6 +887,20 @@ static int resize_is_valid(struct vm_area_struct *vma, unsigned long addr, return 0; } +/* + * mremap_to() - remap a vma to a new location + * @addr: The old address + * @old_len: The old size + * @new_addr: The target address + * @new_len: The new size + * @locked: If the returned vma is locked (VM_LOCKED) + * @flags: the mremap flags + * @uf: The mremap userfaultfd context + * @uf_unmap_early: The userfaultfd unmap early context + * @uf_unmap: The userfaultfd unmap context + * + * Returns: The new address of the vma or an error. + */ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, unsigned long new_addr, unsigned long new_len, bool *locked, unsigned long flags, struct vm_userfaultfd_ctx *uf, @@ -895,18 +909,18 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; - unsigned long ret = -EINVAL; + unsigned long ret; unsigned long map_flags = 0; if (offset_in_page(new_addr)) - goto out; + return -EINVAL; if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) - goto out; + return -EINVAL; /* Ensure the old/new locations do not overlap */ if (addr + old_len > new_addr && new_addr + new_len > addr) - goto out; + return -EINVAL; /* * move_vma() need us to stay 4 maps below the threshold, otherwise @@ -933,31 +947,28 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, */ ret = do_munmap(mm, new_addr, new_len, uf_unmap_early); if (ret) - goto out; + return ret; } if (old_len > new_len) { ret = do_munmap(mm, addr+new_len, old_len - new_len, uf_unmap); if (ret) - goto out; + return ret; old_len = new_len; } vma = vma_lookup(mm, addr); - if (!vma) { - ret = -EFAULT; - goto out; - } + if (!vma) + return -EFAULT; ret = resize_is_valid(vma, addr, old_len, new_len, flags); if (ret) - goto out; + return ret; /* MREMAP_DONTUNMAP expands by old_len since old_len == new_len */ if (flags & MREMAP_DONTUNMAP && !may_expand_vm(mm, vma->vm_flags, old_len >> PAGE_SHIFT)) { - ret = -ENOMEM; - goto out; + return -ENOMEM; } if (flags & MREMAP_FIXED) @@ -970,17 +981,14 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, ((addr - vma->vm_start) >> PAGE_SHIFT), map_flags); if (IS_ERR_VALUE(ret)) - goto out; + return ret; /* We got a new mapping */ if (!(flags & MREMAP_FIXED)) new_addr = ret; - ret = move_vma(vma, addr, old_len, new_len, new_addr, locked, flags, uf, - uf_unmap); - -out: - return ret; + return move_vma(vma, addr, old_len, new_len, new_addr, locked, flags, + uf, uf_unmap); } static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)