Re: [PATCH v3 0/2] iommu/iova: Make the rcache depot properly flexible

[Ethan Zhao]

On 1/2/2024 3:24 PM, Ido Schimmel wrote:
> On Thu, Dec 28, 2023 at 02:23:20PM +0200, Ido Schimmel wrote:
> > On Tue, Sep 12, 2023 at 05:28:04PM +0100, Robin Murphy wrote:
> > > v2: https://lore.kernel.org/linux-iommu/cover.1692641204.git.robin.murphy@xxxxxxx/
> > >
> > > Hi all,
> > >
> > > I hope this is good to go now, just fixed the locking (and threw
> > > lockdep at it to confirm, which of course I should have done to begin
> > > with...) and picked up tags.
> > Hi,
> >
> > After pulling the v6.7 changes we started seeing the following memory
> > leaks [1] of 'struct iova_magazine'. I'm not sure how to reproduce it,
> > which is why I didn't perform bisection. However, looking at the
> > mentioned code paths, they seem to have been changed in v6.7 as part of
> > this patchset. I reverted both patches and didn't see any memory leaks
> > when running a full regression (~10 hours), but I will repeat it to be
> > sure.
> FYI, we didn't see the leaks since reverting these two patches whereas
> before we saw them almost everyday, so I'm quite sure they introduced
> the leaks.

Seems some magazines were not freed when one CPU is dead (hot unplugged) ?

static void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain 
*iovad)
{
    struct iova_cpu_rcache *cpu_rcache;
    struct iova_rcache *rcache;
    unsigned long flags;
    int i;

    for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
        rcache = &iovad->rcaches[i];
        cpu_rcache = per_cpu_ptr(rcache->cpu_rcaches, cpu);
        spin_lock_irqsave(&cpu_rcache->lock, flags);
        iova_magazine_free_pfns(cpu_rcache->loaded, iovad);

+     iova_magazine_free(cpu_rcache->loaded);

        iova_magazine_free_pfns(cpu_rcache->prev, iovad);

+     iova_magazine_free(cpu_rcache->prev);

        spin_unlock_irqrestore(&cpu_rcache->lock, flags);
    }
}



Thanks,

Ethan

> Thanks