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Date: Mon, 15 Jul 2019 20:48:49 +0800 From: Guoheyi <guoheyi@...wei.com> To: Marc Zyngier <marc.zyngier@....com> CC: <linux-kernel@...r.kernel.org>, wanghaibin 00208455 <wanghaibin.wang@...wei.com>, kvmarm <kvmarm@...ts.cs.columbia.edu> Subject: Re: ARM/gic-v4: deadlock occurred On 2019/7/15 19:13, Marc Zyngier wrote: > On 15/07/2019 11:43, Guoheyi wrote: >> >> On 2019/7/15 17:07, Marc Zyngier wrote: >>> On 15/07/2019 07:32, Guoheyi wrote: >>>> Hi Marc, >>>> >>>> The issue only occurs after applying the vlpi_map_rework patches, and we >>>> can see the patches only affect VM; it changes its_create_device() a >>>> little so it may affect host booting in some ways, so I took the lazy >>>> way to send it out for some insights. >>>> >>>> I am suspecting below code; if alloc_lpis == false, what will happen? >>> If !alloc_lpis, then we don't allocate the lpi_map, which is the >>> intended effect. >>> >>>> Anyway, I will investigate more on this. >>>> >>>> >>>> if (alloc_lpis) { >>>> lpi_map = its_lpi_alloc(nvecs, &lpi_base, &nr_lpis); >>>> if (lpi_map) >>>> col_map = kcalloc(nr_lpis, sizeof(*col_map), >>>> GFP_KERNEL); >>>> } else { >>>> col_map = kcalloc(nr_ites, sizeof(*col_map), GFP_KERNEL); >>>> nr_lpis = 0; >>>> lpi_base = 0; >>>> } >>>> if (its->is_v4) >>>> vlpi_map = kcalloc(nr_lpis, sizeof(*vlpi_map), GFP_KERNEL); >>>> >>>> if (!dev || !itt || !col_map || (!lpi_map && alloc_lpis) || >>>> (!vlpi_map && its->is_v4)) { >>>> kfree(dev); >>>> kfree(itt); >>>> kfree(lpi_map); >>>> kfree(col_map); >>>> kfree(vlpi_map); >>>> return NULL; >>>> } >>> How does this relate to the patch posted in this discussion? The >>> proposed changes turn the locking from a mutex into a raw_spinlock. >> I'm testing the patchset in >> https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=irq/vlpi-map-rework, >> not only the patch posted in the mail directly. The first patch >> *"**irqchip/gic-v3-its: Make vlpi_map allocations atomic" works well in >> our internal tree, and my new testing is against the other 3 patches in >> your vlpi-map-rework branch, as I promised. I'm sorry if I didn't state >> this clearly. > Ah, I had completely forgot about this branch. As I said, it is > completely untested. I'll see if I can get some brain bandwidth in the > next couple of weeks to get back to it... Yes, a bit too long ago... And finally I found the panic is caused by this patch: https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?h=irq/vlpi-map-rework&id=fe3dd7e06ee0e82bade4f2a107ef6422e5c9021e diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 18aa04b..6f55886 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -2458,6 +2458,8 @@ static void its_free_device(struct its_device *its_dev) list_del(&its_dev->entry); raw_spin_unlock_irqrestore(&its_dev->its->lock, flags); kfree(its_dev->itt); + kfree(its_dev->event_map.lpi_map); + kfree(its_dev->event_map.col_map); kfree(its_dev); } This patch causes double free for both lpi_map and col_map in its_irq_domain_free(): if (!its_dev->shared && bitmap_empty(its_dev->event_map.lpi_map, its_dev->event_map.nr_lpis)) { its_lpi_free(its_dev->event_map.lpi_map, ----> its_dev->event_map.lpi_map is freed its_dev->event_map.lpi_base, its_dev->event_map.nr_lpis); kfree(its_dev->event_map.col_map); ----> its_dev->event_map.col_map is freed /* Unmap device/itt */ its_send_mapd(its_dev, 0); its_free_device(its_dev); ----> lpi_map and col_map are freed again } Thanks, Heyi > > Thanks, > > M.
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