Re: [PATCH] migration/ram: Fix memory leak when using x-ignore-shared

[Nikolay Borisov]

On 22.09.22 г. 20:42 ч., Dr. David Alan Gilbert wrote:
> * Nikolay Borisov (nborisov@suse.com) wrote:
> > During ram initialization for migration dirty/clear bitmaps are
> > allocated for all migratable blocks, irrespective of their shared
> > status. However, during ram migration cleanup those bitmaps are freed
> > only for those blocks which aren't shared, in case x-ignore-shared
> > capability is used. This leads to a situation where the bitmaps aren't
> > freed for such blocks.
>
> Can you show me where you're seeing the allocation based on MIGRATABLE?
> I'm looking at ram_list_init_bitmaps:
>
>
>          RAMBLOCK_FOREACH_NOT_IGNORED(block) {
>              block->bmap = bitmap_new(pages);
> ....
>              block->clear_bmap = bitmap_new(clear_bmap_size(pages, shift));
>
>
> So that's based on NOT_IGNORED.

Huhz, you are perfectly right and I assume I got confused by the 
RAMBLOCK_FOREACH_MIGRATABLE in ram_save_setup as opposed to the code in 
ram_list_init_bitmaps. Apologies for the noise...

> Dave
>
> > Fix this by switching the cleanup code to also free bitmaps for all
> > migratable blocks.
> >
> > Signed-off-by: Nikolay Borisov <nborisov@suse.com>
> > ---
> >   migration/ram.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/migration/ram.c b/migration/ram.c
> > index dc1de9ddbc68..2e40166d2f9e 100644
> > --- a/migration/ram.c
> > +++ b/migration/ram.c
> > @@ -2678,7 +2678,7 @@ static void ram_save_cleanup(void *opaque)
> >           }
> >       }
> >   
> > -    RAMBLOCK_FOREACH_NOT_IGNORED(block) {
> > +    RAMBLOCK_FOREACH_MIGRATABLE(block) {
> >           g_free(block->clear_bmap);
> >           block->clear_bmap = NULL;
> >           g_free(block->bmap);
> > --
> > 2.34.1