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dkim=pass header.d=gmail.com header.s=20210112 header.b=DsJDBE3r; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf03.hostedemail.com: domain of huangzhaoyang@gmail.com designates 209.85.167.42 as permitted sender) smtp.mailfrom=huangzhaoyang@gmail.com X-Rspam-User: X-Rspamd-Server: rspam01 X-Stat-Signature: og13wk8orab7huwniqg46iuqxbgznxrx X-HE-Tag: 1661586846-808619 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Aug 26, 2022 at 7:49 PM Vlastimil Babka (SUSE) wrote: > > On 8/26/22 08:40, zhaoyang.huang wrote: > > From: Zhaoyang Huang > > > > Kthread and drivers could fetch memory via alloc_pages directly which make them > > hard to debug when leaking. Solve this by introducing __GFP_TRACELEAK and reuse > > kmemleak mechanism which unified most of kernel cosuming pages into kmemleak. > > Can you expand how exactly this is expected to be used? So you first have to > suspect some concrete allocation and add __GFP_TRACKLEAK to it? It could be used to investigate suspicious drivers or kthread which may introduce in-kernel leak during debug phase by enabling kmemleak. This can be done via page owner things now. I would like to unified it together with slab leak into kmemleak. > > > Signed-off-by: Zhaoyang Huang > > --- > > include/linux/gfp.h | 4 +++- > > include/linux/page-flags.h | 3 +++ > > mm/kmemleak.c | 2 +- > > mm/page_alloc.c | 6 ++++++ > > 4 files changed, 13 insertions(+), 2 deletions(-) > > > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > > index 2d2ccae..081ab54 100644 > > --- a/include/linux/gfp.h > > +++ b/include/linux/gfp.h > > @@ -68,6 +68,7 @@ > > #else > > #define ___GFP_NOLOCKDEP 0 > > #endif > > +#define ___GFP_TRACKLEAK 0x10000000u > > /* If the above are modified, __GFP_BITS_SHIFT may need updating */ > > > > /* > > @@ -259,12 +260,13 @@ > > #define __GFP_SKIP_ZERO ((__force gfp_t)___GFP_SKIP_ZERO) > > #define __GFP_SKIP_KASAN_UNPOISON ((__force gfp_t)___GFP_SKIP_KASAN_UNPOISON) > > #define __GFP_SKIP_KASAN_POISON ((__force gfp_t)___GFP_SKIP_KASAN_POISON) > > +#define __GFP_TRACKLEAK ((__force gfp_t)___GFP_TRACKLEAK) > > > > /* Disable lockdep for GFP context tracking */ > > #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP) > > > > /* Room for N __GFP_FOO bits */ > > -#define __GFP_BITS_SHIFT (27 + IS_ENABLED(CONFIG_LOCKDEP)) > > +#define __GFP_BITS_SHIFT (28 + IS_ENABLED(CONFIG_LOCKDEP)) > > #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1)) > > > > /** > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > > index e66f7aa..ef0f814 100644 > > --- a/include/linux/page-flags.h > > +++ b/include/linux/page-flags.h > > @@ -942,6 +942,7 @@ static inline bool is_page_hwpoison(struct page *page) > > #define PG_offline 0x00000100 > > #define PG_table 0x00000200 > > #define PG_guard 0x00000400 > > +#define PG_trackleak 0x00000800 > > > > #define PageType(page, flag) \ > > ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE) > > @@ -1012,6 +1013,8 @@ static inline int page_has_type(struct page *page) > > */ > > PAGE_TYPE_OPS(Guard, guard) > > > > +PAGE_TYPE_OPS(Trackleak, trackleak) > > + > > extern bool is_free_buddy_page(struct page *page); > > > > PAGEFLAG(Isolated, isolated, PF_ANY); > > diff --git a/mm/kmemleak.c b/mm/kmemleak.c > > index 422f28f..a182f5d 100644 > > --- a/mm/kmemleak.c > > +++ b/mm/kmemleak.c > > @@ -1471,7 +1471,7 @@ static void kmemleak_scan(void) > > if (page_zone(page) != zone) > > continue; > > /* only scan if page is in use */ > > - if (page_count(page) == 0 || PageReserved(page)) > > + if (page_count(page) == 0) > > continue; > > scan_block(page, page + 1, NULL); > > if (!(pfn & 63)) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index e008a3d..d8995c6 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -1361,6 +1361,8 @@ static __always_inline bool free_pages_prepare(struct page *page, > > page->mapping = NULL; > > if (memcg_kmem_enabled() && PageMemcgKmem(page)) > > __memcg_kmem_uncharge_page(page, order); > > + if (PageTrackleak(page)) > > + kmemleak_free(page); > > if (check_free) > > bad += check_free_page(page); > > if (bad) > > @@ -5444,6 +5446,10 @@ struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid, > > __free_pages(page, order); > > page = NULL; > > } > > + if (gfp & __GFP_TRACKLEAK) { > > + kmemleak_alloc(page_address(page), PAGE_SIZE << order, 1, gfp & ~__GFP_TRACKLEAK); > > + __SetPageTrackleak(page); > > + } > > > > trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype); > > >