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From: Christoph Hellwig <hch@lst.de>
To: Minchan Kim <minchan@kernel.org>
Cc: Juergen Gross <jgross@suse.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	dri-devel@lists.freedesktop.org, xen-devel@lists.xenproject.org,
	Andrew Morton <akpm@linux-foundation.org>,
	intel-gfx@lists.freedesktop.org, Christoph Hellwig <hch@lst.de>,
	Nitin Gupta <ngupta@vflare.org>
Subject: Re: [Intel-gfx] [PATCH 1/6] zsmalloc: switch from alloc_vm_area to get_vm_area
Date: Mon, 21 Sep 2020 20:17:08 +0200
Message-ID: <20200921181708.GA2067@lst.de> (raw)
In-Reply-To: <20200921174256.GA387368@google.com>

On Mon, Sep 21, 2020 at 10:42:56AM -0700, Minchan Kim wrote:
> IIRC, the problem was runtime pte popluating needs GFP_KERNEL but
> zs_map_object API runs under non-preemtible section.

Make sense.

> > -	area->vm = alloc_vm_area(PAGE_SIZE * 2, NULL);
> > +	area->vm = get_vm_area(PAGE_SIZE * 2, 0);
> >  	if (!area->vm)
> >  		return -ENOMEM;
> >  	return 0;
> 
> I think it shoud work.
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index 05789aa4af12..6a1e4d854593 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2232,7 +2232,7 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
>  	arch_enter_lazy_mmu_mode();
>  
>  	do {
> -		if (create || !pte_none(*pte)) {
> +		if ((create || !pte_none(*pte)) && fn) {
>  			err = fn(pte++, addr, data);
>  			if (err)
>  				break;
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 3e4fe3259612..9ef7daf3d279 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -1116,6 +1116,8 @@ static struct zspage *find_get_zspage(struct size_class *class)
>  #ifdef CONFIG_ZSMALLOC_PGTABLE_MAPPING
>  static inline int __zs_cpu_up(struct mapping_area *area)
>  {
> +	int ret;
> +
>  	/*
>  	 * Make sure we don't leak memory if a cpu UP notification
>  	 * and zs_init() race and both call zs_cpu_up() on the same cpu
> @@ -1125,7 +1127,13 @@ static inline int __zs_cpu_up(struct mapping_area *area)
>  	area->vm = get_vm_area(PAGE_SIZE * 2, 0);
>  	if (!area->vm)
>  		return -ENOMEM;
> -	return 0;
> +
> +	/*
> +	 * Populate ptes in advance to avoid pte allocation with GFP_KERNEL
> +	 * in non-preemtible context of zs_map_object.
> +	 */
> +	ret = apply_to_page_range(&init_mm, NULL, PAGE_SIZE * 2, NULL, NULL);
> +	return ret;

I think this needs the addr from the vm area somewhere..

We probaby want to add a trivial helper to prefault an area instead of
the open coded variant.
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  reply index

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-18 16:37 [Intel-gfx] remove alloc_vm_area Christoph Hellwig
2020-09-18 16:37 ` [Intel-gfx] [PATCH 1/6] zsmalloc: switch from alloc_vm_area to get_vm_area Christoph Hellwig
2020-09-21 17:42   ` Minchan Kim
2020-09-21 18:17     ` Christoph Hellwig [this message]
2020-09-21 18:42       ` Minchan Kim
2020-09-21 18:43         ` Christoph Hellwig
2020-09-18 16:37 ` [Intel-gfx] [PATCH 2/6] mm: add a vmap_pfn function Christoph Hellwig
2020-09-18 16:37 ` [Intel-gfx] [PATCH 3/6] drm/i915: use vmap in shmem_pin_map Christoph Hellwig
2020-09-21 19:11   ` Matthew Wilcox
2020-09-22  6:22     ` Christoph Hellwig
2020-09-22  8:23       ` Tvrtko Ursulin
2020-09-22 14:31         ` Christoph Hellwig
2020-09-22 16:13           ` Tvrtko Ursulin
2020-09-22 16:33             ` Christoph Hellwig
2020-09-22 17:04               ` Tvrtko Ursulin
2020-09-23  6:11                 ` Christoph Hellwig
2020-09-22 11:21       ` Matthew Wilcox
2020-09-22 14:39         ` Christoph Hellwig
2020-09-22 14:53           ` Matthew Wilcox
2020-09-18 16:37 ` [Intel-gfx] [PATCH 4/6] drm/i915: use vmap in i915_gem_object_map Christoph Hellwig
2020-09-23  9:52   ` Tvrtko Ursulin
2020-09-23 13:41     ` Christoph Hellwig
2020-09-23 13:58       ` Tvrtko Ursulin
2020-09-23 14:44         ` Christoph Hellwig
2020-09-24 12:22           ` Tvrtko Ursulin
2020-09-24 13:23             ` Christoph Hellwig
2020-09-18 16:37 ` [Intel-gfx] [PATCH 5/6] xen/xenbus: use apply_to_page_range directly in xenbus_map_ring_pv Christoph Hellwig
2020-09-18 16:37 ` [Intel-gfx] [PATCH 6/6] x86/xen: open code alloc_vm_area in arch_gnttab_valloc Christoph Hellwig
2020-09-21 20:44   ` boris.ostrovsky
2020-09-22 14:58     ` Christoph Hellwig
2020-09-22 15:24       ` boris.ostrovsky
2020-09-22 15:27         ` Christoph Hellwig
2020-09-22 15:34           ` boris.ostrovsky
2020-09-18 17:03 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for series starting with [1/6] zsmalloc: switch from alloc_vm_area to get_vm_area Patchwork
2020-09-21 17:50 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for series starting with [1/6] zsmalloc: switch from alloc_vm_area to get_vm_area (rev2) Patchwork
2020-09-21 18:47 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for series starting with [1/6] zsmalloc: switch from alloc_vm_area to get_vm_area (rev3) Patchwork
2020-09-22 14:44 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for series starting with [1/6] zsmalloc: switch from alloc_vm_area to get_vm_area (rev4) Patchwork
2020-09-22 15:01 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for series starting with [1/6] zsmalloc: switch from alloc_vm_area to get_vm_area (rev5) Patchwork

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