On Thu, May 30, 2024 at 5:16 PM Chuanhua Han <chuanhuahan@xxxxxxxxx> wrote:
>
> zhaoyang.huang <zhaoyang.huang@xxxxxxxxxx> 于2024年5月30日周四 10:52写道：
> >
> > From: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
> >
> > Broken vbq->free reported on a v6.6 based system which is caused
> > by invalid vbq->lock protect over vbq->free in purge_fragmented_block.
> > This should be introduced by the Fixes below which ignored vbq->lock
> > matter.
> >
> > Fixes: fc1e0d980037 ("mm/vmalloc: prevent stale TLBs in fully utilized blocks")
> >
> > Signed-off-by: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
> > ---
> > mm/vmalloc.c | 11 +++++++----
> > 1 file changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > index 22aa63f4ef63..112b50431725 100644
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -2614,9 +2614,10 @@ static void free_vmap_block(struct vmap_block *vb)
> > }
> >
> > static bool purge_fragmented_block(struct vmap_block *vb,
> > - struct vmap_block_queue *vbq, struct list_head *purge_list,
> > - bool force_purge)
> > + struct list_head *purge_list, bool force_purge)
> > {
> > + struct vmap_block_queue *vbq;
> > +
> > if (vb->free + vb->dirty != VMAP_BBMAP_BITS ||
> > vb->dirty == VMAP_BBMAP_BITS)
> > return false;
> > @@ -2625,6 +2626,8 @@ static bool purge_fragmented_block(struct vmap_block *vb,
> > if (!(force_purge || vb->free < VMAP_PURGE_THRESHOLD))
> > return false;
> >
> > + vbq = container_of(addr_to_vb_xa(vb->va->va_start),
> > + struct vmap_block_queue, vmap_blocks);
> This seems to be the same as before fix :), the vbq found by
> addr_to_vb_xa is still added to the xarray vbq, not necessarily to the
> free_list vbq,
Yes, my fault. Should we expand the vmap_block_queue by introducing a
cpu_id which I actually do in my local regression.
> These two vbqs may not be the same, we need to find the vbq when added
> to free_list.
>
> For example:
> We add vb to vbq1's xarray and vbq2's free_list, and we need to find
> vbq2 instead of vbq1.
> So I feel like this place isn't really fixed？
> > /* prevent further allocs after releasing lock */
> > WRITE_ONCE(vb->free, 0);
> > /* prevent purging it again */
> > @@ -2664,7 +2667,7 @@ static void purge_fragmented_blocks(int cpu)
> > continue;
> >
> > spin_lock(&vb->lock);
> > - purge_fragmented_block(vb, vbq, &purge, true);
> > + purge_fragmented_block(vb, &purge, true);
> > spin_unlock(&vb->lock);
> > }
> > rcu_read_unlock();
> > @@ -2801,7 +2804,7 @@ static void _vm_unmap_aliases(unsigned long start, unsigned long end, int flush)
> > * not purgeable, check whether there is dirty
> > * space to be flushed.
> > */
> > - if (!purge_fragmented_block(vb, vbq, &purge_list, false) &&
> > + if (!purge_fragmented_block(vb, &purge_list, false) &&
> > vb->dirty_max && vb->dirty != VMAP_BBMAP_BITS) {
> > unsigned long va_start = vb->va->va_start;
> > unsigned long s, e;
> > --
> > 2.25.1
> >
> >
>
>
> --
> Thanks,
> Chuanhua
