similar to: [PATCH] virtio: avoid possible OOM lockup at virtballoon_oom_notify()

Hello. I noticed that virtio_balloon is using register_oom_notifier() and leak_balloon() from virtballoon_oom_notify() might depend on __GFP_DIRECT_RECLAIM memory allocation. In leak_balloon(), mutex_lock(&vb->balloon_lock) is called in order to serialize against fill_balloon(). But in fill_balloon(), alloc_page(GFP_HIGHUSER[_MOVABLE] | __GFP_NOMEMALLOC | __GFP_NORETRY) is called with

Hello. I noticed that virtio_balloon is using register_oom_notifier() and leak_balloon() from virtballoon_oom_notify() might depend on __GFP_DIRECT_RECLAIM memory allocation. In leak_balloon(), mutex_lock(&vb->balloon_lock) is called in order to serialize against fill_balloon(). But in fill_balloon(), alloc_page(GFP_HIGHUSER[_MOVABLE] | __GFP_NOMEMALLOC | __GFP_NORETRY) is called with

On Sat, Oct 14, 2017 at 01:41:14AM +0900, Tetsuo Handa wrote: > Michael S. Tsirkin wrote: > > On Tue, Oct 10, 2017 at 07:47:37PM +0900, Tetsuo Handa wrote: > > > In leak_balloon(), mutex_lock(&vb->balloon_lock) is called in order to > > > serialize against fill_balloon(). But in fill_balloon(), > > > alloc_page(GFP_HIGHUSER[_MOVABLE] | __GFP_NOMEMALLOC |

On Sat, Oct 14, 2017 at 01:41:14AM +0900, Tetsuo Handa wrote: > Michael S. Tsirkin wrote: > > On Tue, Oct 10, 2017 at 07:47:37PM +0900, Tetsuo Handa wrote: > > > In leak_balloon(), mutex_lock(&vb->balloon_lock) is called in order to > > > serialize against fill_balloon(). But in fill_balloon(), > > > alloc_page(GFP_HIGHUSER[_MOVABLE] | __GFP_NOMEMALLOC |

fill_balloon doing memory allocations under balloon_lock can cause a deadlock when leak_balloon is called from virtballoon_oom_notify and tries to take same lock. To fix, split page allocation and enqueue and do allocations outside the lock. Here's a detailed analysis of the deadlock by Tetsuo Handa: In leak_balloon(), mutex_lock(&vb->balloon_lock) is called in order to serialize

fill_balloon doing memory allocations under balloon_lock can cause a deadlock when leak_balloon is called from virtballoon_oom_notify and tries to take same lock. To fix, split page allocation and enqueue and do allocations outside the lock. Here's a detailed analysis of the deadlock by Tetsuo Handa: In leak_balloon(), mutex_lock(&vb->balloon_lock) is called in order to serialize

fill_balloon doing memory allocations under balloon_lock can cause a deadlock when leak_balloon is called from virtballoon_oom_notify and tries to take same lock. To fix, split page allocation and enqueue and do allocations outside the lock. Here's a detailed analysis of the deadlock by Tetsuo Handa: In leak_balloon(), mutex_lock(&vb->balloon_lock) is called in order to serialize

fill_balloon doing memory allocations under balloon_lock can cause a deadlock when leak_balloon is called from virtballoon_oom_notify and tries to take same lock. To fix, split page allocation and enqueue and do allocations outside the lock. Here's a detailed analysis of the deadlock by Tetsuo Handa: In leak_balloon(), mutex_lock(&vb->balloon_lock) is called in order to serialize

Tetsuo Handa wrote: > Michael S. Tsirkin wrote: > > > > > > > > The proper fix isn't that hard - just avoid allocations under lock. > > > > > > > > Patch posted, pls take a look. > > > > > > Your patch allocates pages in order to inflate the balloon, but > > > your patch will allow leak_balloon() to deflate the

Tetsuo Handa wrote: > Michael S. Tsirkin wrote: > > > > > > > > The proper fix isn't that hard - just avoid allocations under lock. > > > > > > > > Patch posted, pls take a look. > > > > > > Your patch allocates pages in order to inflate the balloon, but > > > your patch will allow leak_balloon() to deflate the

On Sat, Sep 30, 2017 at 12:05:52PM +0800, Wei Wang wrote: > +static inline void xb_set_page(struct virtio_balloon *vb, > + struct page *page, > + unsigned long *pfn_min, > + unsigned long *pfn_max) > +{ > + unsigned long pfn = page_to_pfn(page); > + > + *pfn_min = min(pfn, *pfn_min); > + *pfn_max = max(pfn, *pfn_max); > +

On Sat, Sep 30, 2017 at 12:05:52PM +0800, Wei Wang wrote: > +static inline void xb_set_page(struct virtio_balloon *vb, > + struct page *page, > + unsigned long *pfn_min, > + unsigned long *pfn_max) > +{ > + unsigned long pfn = page_to_pfn(page); > + > + *pfn_min = min(pfn, *pfn_min); > + *pfn_max = max(pfn, *pfn_max); > +

Wei Wang wrote: > The balloon_lock was used to synchronize the access demand to elements > of struct virtio_balloon and its queue operations (please see commit > e22504296d). This prevents the concurrent run of the leak_balloon and > fill_balloon functions, thereby resulting in a deadlock issue on OOM: > > fill_balloon: take balloon_lock and wait for OOM to get some memory; >

Wei Wang wrote: > The balloon_lock was used to synchronize the access demand to elements > of struct virtio_balloon and its queue operations (please see commit > e22504296d). This prevents the concurrent run of the leak_balloon and > fill_balloon functions, thereby resulting in a deadlock issue on OOM: > > fill_balloon: take balloon_lock and wait for OOM to get some memory; >

This patch series intends to summarize the recent contributions made by Michael S. Tsirkin, Tetsuo Handa, Michal Hocko etc. via reporting and discussing the related deadlock issues on the mailinglist. Please check each patch for details. >From a high-level point of view, this patch series achieves: 1) eliminate the deadlock issue fundamentally caused by the inability to run leak_balloon and

This patch series intends to summarize the recent contributions made by Michael S. Tsirkin, Tetsuo Handa, Michal Hocko etc. via reporting and discussing the related deadlock issues on the mailinglist. Please check each patch for details. >From a high-level point of view, this patch series achieves: 1) eliminate the deadlock issue fundamentally caused by the inability to run leak_balloon and

Tetsuo Handa wrote: > 20171016-deflate.log.xz continued printing "puff" messages without any OOM > killer messages, for fill_balloon() always inflates faster than leak_balloon() > deflates. > > Since the OOM killer cannot be invoked unless leak_balloon() completely > deflates faster than fill_balloon() inflates, the guest remained unusable > (e.g. unable to login

Tetsuo Handa wrote: > 20171016-deflate.log.xz continued printing "puff" messages without any OOM > killer messages, for fill_balloon() always inflates faster than leak_balloon() > deflates. > > Since the OOM killer cannot be invoked unless leak_balloon() completely > deflates faster than fill_balloon() inflates, the guest remained unusable > (e.g. unable to login

This patch series enhances the existing virtio-balloon with the following new features: 1) fast ballooning: transfer ballooned pages between the guest and host in chunks using sgs, instead of one array each time; and 2) free page block reporting: a new virtqueue to report guest free pages to the host. The second feature can be used to accelerate live migration of VMs. Here are some details: Live

This patch series enhances the existing virtio-balloon with the following new features: 1) fast ballooning: transfer ballooned pages between the guest and host in chunks using sgs, instead of one array each time; and 2) free page block reporting: a new virtqueue to report guest free pages to the host. The second feature can be used to accelerate live migration of VMs. Here are some details: Live