On Fri, Oct 25, 2024 at 07:40:43PM +0200, Vlastimil Babka wrote:
> On 10/25/24 14:26, Lorenzo Stoakes wrote:
> > Rather than trying to merge again when ostensibly allocating a new VMA,
> > instead defer until the VMA is added and attempt to merge the existing
> > range.
> >
> > This way we have no complicated unwinding logic midway through the process
> > of mapping the VMA.
> >
> > In addition this removes limitations on the VMA not being able to be the
> > first in the virtual memory address space which was previously implicitly
> > required.
> >
> > In theory, for this very same reason, we should unconditionally attempt
> > merge here, however this is likely to have a performance impact so it is
> > better to avoid this given the unlikely outcome of a merge.
> >
> > Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
> > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
> > ---
> > mm/vma.c | 55 ++++++++++++++-----------------------------------------
> > 1 file changed, 14 insertions(+), 41 deletions(-)
> >
> > diff --git a/mm/vma.c b/mm/vma.c
> > index 7c690be67910..7194f9449c60 100644
> > --- a/mm/vma.c
> > +++ b/mm/vma.c
> > @@ -19,6 +19,7 @@ struct mmap_state {
> > struct file *file;
> >
> > unsigned long charged;
> > + bool retry_merge;
> >
> > struct vm_area_struct *prev;
> > struct vm_area_struct *next;
> > @@ -2278,8 +2279,9 @@ static int __mmap_prepare(struct mmap_state *map, struct list_head *uf)
> > return 0;
> > }
> >
> > +
> > static int __mmap_new_file_vma(struct mmap_state *map,
> > - struct vm_area_struct **vmap, bool *mergedp)
> > + struct vm_area_struct **vmap)
>
> AFAICS **vmap could become *vma now
Ah yeah good spot you're right, will chase up on respin or do a fix-patch
next week!
>
> > {
> > struct vma_iterator *vmi = map->vmi;
> > struct vm_area_struct *vma = *vmap;
