search for: set_page_count

...t; something that is not system memory. For both the ppc kvm case (magic > hypervisor pool) and Noveau (device internal) memory that clear is the > case. But looks like test_hmm uses normal pages to fake this up, so > I was wrong about the third caller. But I think we can just call > set_page_count just before freeing the page there with a comment > explaining what is goin on. Dan Williams thought that having the ZONE_DEVICE struct pages be on a free list with a refcount of one was a bit strange and that the driver should handle the zero to one transition. But, that would mean a bit more...

...5/20 9:29 AM, Christoph Hellwig wrote: > On Mon, Sep 14, 2020 at 04:53:25PM -0700, Ralph Campbell wrote: >> Since set_page_refcounted() is defined in mm_interal.h I would have to >> move the definition to someplace like page_ref.h or have the drivers >> cal init_page_count() or set_page_count() since get_page() calls >> VM_BUG_ON_PAGE() if refcount == 0. >> I'll move set_page_refcounted() since that is what the page allocator >> uses and seems named for the purpose. > > I don't think any of the three ->page_free instances even cares about > the pag...

...zero to the wider kernel but expect that drivers > get a fake reference on entry to their ->page_free() callbacks. Good point. Since set_page_refcounted() is defined in mm_interal.h I would have to move the definition to someplace like page_ref.h or have the drivers cal init_page_count() or set_page_count() since get_page() calls VM_BUG_ON_PAGE() if refcount == 0. I'll move set_page_refcounted() since that is what the page allocator uses and seems named for the purpose.

Running with Xen option dom0_mem=6G and kernel option mem=8G, I would have expected that I would see the system with a 2G balloon right after boot. However, the balloon is empty. Briefly looking at this, it would seem to me that, with all pages being reserved when the system starts and only the populated ones getting the reserved status cleared in __free_pages_bootmem(), the condition to put pages

...@@ int kvmppc_uvmem_init(void) goto out_unmap; } + /* + * Pages are created with an initial reference count of one but should + * have a reference count of zero while in the free state. + */ + for (pfn = pfn_first; pfn < pfn_last; pfn++) { + struct page *dpage = pfn_to_page(pfn); + + set_page_count(dpage, 0); + } + pr_info("KVMPPC-UVMEM: Secure Memory size 0x%lx\n", size); return ret; out_unmap: diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c index 92987daa5e17..8bc7120e1216 100644 --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c +++ b/d...

...kmap_flush_unused(); + op.cmd = MMUEXT_PIN_L1_TABLE; + op.arg1.mfn = pfn_to_mfn(page_to_pfn(pte)); + BUG_ON(HYPERVISOR_mmuext_op(&op, 1, NULL, DOMID_SELF) < 0); + } #else pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO, 0); +#endif if (pte) { SetPageForeign(pte, pte_free); set_page_count(pte, 1); } -#endif return pte; } void pte_free(struct page *pte) { - unsigned long va = (unsigned long)__va(page_to_pfn(pte)<<PAGE_SHIFT); + unsigned long pfn = page_to_pfn(pte); - if (!pte_write(*virt_to_ptep(va))) - BUG_ON(HYPERVISOR_update_va_mapping( - va, pfn_pte(page_to_pf...

...gain the reference back to balance the > >>> MEM_GOING_OFFLINE step. > >> > >> The pages are already unisolated and could be used by the buddy. But again, > >> I think you have an idea that tries to avoid putting pages to the buddy. > > > > Yeah, set_page_count(page, 0) if you do not want to release that page > > from the notifier context to reflect that the page is ok to be offlined > > with the rest. > > > > I neither see how you deal with __test_page_isolated_in_pageblock() nor with > __offline_isolated_pages(). Sorry, bu...

...EM_GOING_OFFLINE. > > MEM_CANCEL_OFFLINE could gain the reference back to balance the > > MEM_GOING_OFFLINE step. > > The pages are already unisolated and could be used by the buddy. But again, > I think you have an idea that tries to avoid putting pages to the buddy. Yeah, set_page_count(page, 0) if you do not want to release that page from the notifier context to reflect that the page is ok to be offlined with the rest. [...] > > explicit control via the reference count which is the standard way to > > control the struct page life cycle. > > > > Anyway...

...gain the reference back to balance the > >>> MEM_GOING_OFFLINE step. > >> > >> The pages are already unisolated and could be used by the buddy. But again, > >> I think you have an idea that tries to avoid putting pages to the buddy. > > > > Yeah, set_page_count(page, 0) if you do not want to release that page > > from the notifier context to reflect that the page is ok to be offlined > > with the rest. > > > > I neither see how you deal with __test_page_isolated_in_pageblock() nor with > __offline_isolated_pages(). Sorry, bu...

...EM_GOING_OFFLINE. > > MEM_CANCEL_OFFLINE could gain the reference back to balance the > > MEM_GOING_OFFLINE step. > > The pages are already unisolated and could be used by the buddy. But again, > I think you have an idea that tries to avoid putting pages to the buddy. Yeah, set_page_count(page, 0) if you do not want to release that page from the notifier context to reflect that the page is ok to be offlined with the rest. [...] > > explicit control via the reference count which is the standard way to > > control the struct page life cycle. > > > > Anyway...

On Mon, Sep 14, 2020 at 04:53:25PM -0700, Ralph Campbell wrote: > Since set_page_refcounted() is defined in mm_interal.h I would have to > move the definition to someplace like page_ref.h or have the drivers > cal init_page_count() or set_page_count() since get_page() calls > VM_BUG_ON_PAGE() if refcount == 0. > I'll move set_page_refcounted() since that is what the page allocator > uses and seems named for the purpose. I don't think any of the three ->page_free instances even cares about the page refcount.

...have a struct page for something that is not system memory. For both the ppc kvm case (magic hypervisor pool) and Noveau (device internal) memory that clear is the case. But looks like test_hmm uses normal pages to fake this up, so I was wrong about the third caller. But I think we can just call set_page_count just before freeing the page there with a comment explaining what is goin on.

...s are created with an initial reference count of one but should > + * have a reference count of zero while in the free state. > + */ > spin_lock(&mdevice->lock); > for (pfn = pfn_first; pfn < pfn_last; pfn++) { > struct page *page = pfn_to_page(pfn); > > + set_page_count(page, 0); This confuses me. How does this and init_page_count() not confuse the buddy allocator? Don't you have to reset the refcount somewhere after the test? > page->zone_device_data = mdevice->free_pages; > mdevice->free_pages = page; > } > @@ -561,7 +566,7 @...

...@@ int kvmppc_uvmem_init(void) goto out_unmap; } + /* + * Pages are created with an initial reference count of one but should + * have a reference count of zero while in the free state. + */ + for (pfn = pfn_first; pfn < pfn_last; pfn++) { + struct page *dpage = pfn_to_page(pfn); + + set_page_count(dpage, 0); + } + pr_info("KVMPPC-UVMEM: Secure Memory size 0x%lx\n", size); return ret; out_unmap: diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c index 92987daa5e17..8bc7120e1216 100644 --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c +++ b/d...

hi I try to understand the code of balloon ,and got confused about the following parts of code: static int decrease_reservation(unsigned long nr_pages) { .... if (!PageHighMem(page)) { v = phys_to_virt(pfn << PAGE_SHIFT); scrub_pages(v, 1); ret = HYPERVISOR_update_va_mapping( (unsigned long)v, __pte_ma(0), 0);

...ce back to balance the >>>>> MEM_GOING_OFFLINE step. >>>> >>>> The pages are already unisolated and could be used by the buddy. But again, >>>> I think you have an idea that tries to avoid putting pages to the buddy. >>> >>> Yeah, set_page_count(page, 0) if you do not want to release that page >>> from the notifier context to reflect that the page is ok to be offlined >>> with the rest. >>> >> >> I neither see how you deal with __test_page_isolated_in_pageblock() nor with >> __offline_isolat...

...;> MEM_CANCEL_OFFLINE could gain the reference back to balance the >>> MEM_GOING_OFFLINE step. >> >> The pages are already unisolated and could be used by the buddy. But again, >> I think you have an idea that tries to avoid putting pages to the buddy. > > Yeah, set_page_count(page, 0) if you do not want to release that page > from the notifier context to reflect that the page is ok to be offlined > with the rest. > I neither see how you deal with __test_page_isolated_in_pageblock() nor with __offline_isolated_pages(). Sorry, but what I read is incomplete an...

...c.c b/mm/page_alloc.c index fab5e97dc9ca..397b0765de97 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6070,6 +6070,9 @@ void __ref memmap_init_zone_device(struct zone *zone, __init_single_page(page, pfn, zone_idx, nid); + /* ZONE_DEVICE pages start with a zero reference count. */ + set_page_count(page, 0); + /* * Mark page reserved as it will need to wait for onlining * phase for it to be fully associated with a zone. diff --git a/mm/swap.c b/mm/swap.c index e7bdf094f76a..769644fe70ef 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -116,12 +116,11 @@ static void __put_compound_page(str...

...c.c b/mm/page_alloc.c index eb0962976a0e..039b88bb3978 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6154,6 +6154,9 @@ void __ref memmap_init_zone_device(struct zone *zone, __init_single_page(page, pfn, zone_idx, nid); + /* ZONE_DEVICE pages start with a zero reference count. */ + set_page_count(page, 0); + /* * Mark page reserved as it will need to wait for onlining * phase for it to be fully associated with a zone. diff --git a/mm/swap.c b/mm/swap.c index 0eb057141a04..82cbe069dcf3 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -116,12 +116,11 @@ static void __put_compound_page(str...

On Fri 18-10-19 10:50:24, David Hildenbrand wrote: > On 18.10.19 10:15, Michal Hocko wrote: > > On Wed 16-10-19 16:14:52, David Hildenbrand wrote: > > > On 16.10.19 16:03, Michal Hocko wrote: > > [...] > > > > But why cannot you keep the reference count at 1 (do get_page when > > > > offlining the page)? In other words as long as the driver knows the