| Message ID | 20180710165326.9378-1-willy@infradead.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 07/10/2018 07:53 PM, Matthew Wilcox wrote: > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 21e1b6a9f113..8a4698b368de 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -153,6 +153,11 @@ struct page { > spinlock_t ptl; > #endif > }; > + struct { /* VMalloc pages */ > + struct vm_struct *vm_area; > + unsigned long vm_offset; > + unsigned long _vm_id; /* MAPPING_VMalloc */ > + }; > struct { /* ZONE_DEVICE pages */ > /** @pgmap: Points to the hosting device page map. */ > struct dev_pagemap *pgmap; > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index 901943e4754b..588b8dd28a85 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -699,6 +699,32 @@ PAGE_TYPE_OPS(Kmemcg, kmemcg) > */ > PAGE_TYPE_OPS(Table, table) > > +/* > + * vmalloc pages may be mapped to userspace, so we need some other way > + * to distinguish them from other kinds of pages. Use page->mapping for > + * this purpose. Values below 0x1000 cannot be real pointers. Setting > + * the bottom bit makes page_mapping() return NULL, which is what we want. > + */ > +#define MAPPING_VMalloc (void *)0x441 So this makes the vmalloc pages look like anon pages, while previously they were !PageAnon. I'm pretty sure this is not going to work. > + > +#define PAGE_MAPPING_OPS(name) \ > +static __always_inline int Page##name(struct page *page) \ > +{ \ > + return page->mapping == MAPPING_##name; \ > +} \ > +static __always_inline void __SetPage##name(struct page *page) \ > +{ \ > + VM_BUG_ON_PAGE(page->mapping != NULL, page); \ > + page->mapping = MAPPING_##name; \ > +} \ > +static __always_inline void __ClearPage##name(struct page *page) \ > +{ \ > + VM_BUG_ON_PAGE(page->mapping != MAPPING_##name, page); \ > + page->mapping = NULL; \ > +} > + > +PAGE_MAPPING_OPS(VMalloc) > +
diff --git a/fs/proc/page.c b/fs/proc/page.c index 792c78a49174..fc83dae1af7b 100644 --- a/fs/proc/page.c +++ b/fs/proc/page.c @@ -156,6 +156,8 @@ u64 stable_page_flags(struct page *page) u |= 1 << KPF_BALLOON; if (PageTable(page)) u |= 1 << KPF_PGTABLE; + if (PageVMalloc(page)) + u |= 1 << KPF_VMALLOC; if (page_is_idle(page)) u |= 1 << KPF_IDLE; diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 21e1b6a9f113..8a4698b368de 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -153,6 +153,11 @@ struct page { spinlock_t ptl; #endif }; + struct { /* VMalloc pages */ + struct vm_struct *vm_area; + unsigned long vm_offset; + unsigned long _vm_id; /* MAPPING_VMalloc */ + }; struct { /* ZONE_DEVICE pages */ /** @pgmap: Points to the hosting device page map. */ struct dev_pagemap *pgmap; diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 901943e4754b..588b8dd28a85 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -699,6 +699,32 @@ PAGE_TYPE_OPS(Kmemcg, kmemcg) */ PAGE_TYPE_OPS(Table, table) +/* + * vmalloc pages may be mapped to userspace, so we need some other way + * to distinguish them from other kinds of pages. Use page->mapping for + * this purpose. Values below 0x1000 cannot be real pointers. Setting + * the bottom bit makes page_mapping() return NULL, which is what we want. + */ +#define MAPPING_VMalloc (void *)0x441 + +#define PAGE_MAPPING_OPS(name) \ +static __always_inline int Page##name(struct page *page) \ +{ \ + return page->mapping == MAPPING_##name; \ +} \ +static __always_inline void __SetPage##name(struct page *page) \ +{ \ + VM_BUG_ON_PAGE(page->mapping != NULL, page); \ + page->mapping = MAPPING_##name; \ +} \ +static __always_inline void __ClearPage##name(struct page *page) \ +{ \ + VM_BUG_ON_PAGE(page->mapping != MAPPING_##name, page); \ + page->mapping = NULL; \ +} + +PAGE_MAPPING_OPS(VMalloc) + extern bool is_free_buddy_page(struct page *page); __PAGEFLAG(Isolated, isolated, PF_ANY); diff --git a/include/uapi/linux/kernel-page-flags.h b/include/uapi/linux/kernel-page-flags.h index 21b9113c69da..6800968b8f47 100644 --- a/include/uapi/linux/kernel-page-flags.h +++ b/include/uapi/linux/kernel-page-flags.h @@ -36,5 +36,6 @@ #define KPF_ZERO_PAGE 24 #define KPF_IDLE 25 #define KPF_PGTABLE 26 +#define KPF_VMALLOC 27 #endif /* _UAPILINUX_KERNEL_PAGE_FLAGS_H */ diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 1863390fa09c..99331453e114 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1522,7 +1522,7 @@ static void __vunmap(const void *addr, int deallocate_pages) for (i = 0; i < area->nr_pages; i++) { struct page *page = area->pages[i]; - BUG_ON(!page); + __ClearPageVMalloc(page); __free_pages(page, 0); } @@ -1691,6 +1691,9 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, area->nr_pages = i; goto fail; } + __SetPageVMalloc(page); + page->vm_area = area; + page->vm_offset = i; area->pages[i] = page; if (gfpflags_allow_blocking(gfp_mask)) cond_resched(); diff --git a/tools/vm/page-types.c b/tools/vm/page-types.c index cce853dca691..25cc21855be4 100644 --- a/tools/vm/page-types.c +++ b/tools/vm/page-types.c @@ -132,6 +132,7 @@ static const char * const page_flag_names[] = { [KPF_THP] = "t:thp", [KPF_BALLOON] = "o:balloon", [KPF_PGTABLE] = "g:pgtable", + [KPF_VMALLOC] = "V:vmalloc", [KPF_ZERO_PAGE] = "z:zero_page", [KPF_IDLE] = "i:idle_page",
For diagnosing various performance and memory-leak problems, it is helpful to be able to distinguish pages which are in use as VMalloc pages. Unfortunately, we cannot use the page_type field in struct page, as this is in use for mapcount by some drivers which map vmalloced pages to userspace. Use a special page->mapping value to distinguish VMalloc pages from other kinds of pages. Also record a pointer to the vm_struct and the offset within the area in struct page to help reconstruct exactly what this page is being used for. Signed-off-by: Matthew Wilcox <willy@infradead.org> --- v7: Use a value which has the bottom bit set so that page_mapping() returns NULL. Comments updated to note this bit of "cleverness". fs/proc/page.c | 2 ++ include/linux/mm_types.h | 5 +++++ include/linux/page-flags.h | 26 ++++++++++++++++++++++++++ include/uapi/linux/kernel-page-flags.h | 1 + mm/vmalloc.c | 5 ++++- tools/vm/page-types.c | 1 + 6 files changed, 39 insertions(+), 1 deletion(-)