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Date: Fri, 2 Sep 2022 11:58:39 -0700 From: Andrew Morton <akpm@...ux-foundation.org> To: "zhaoyang.huang" <zhaoyang.huang@...soc.com> Cc: Catalin Marinas <catalin.marinas@....com>, Zhaoyang Huang <huangzhaoyang@...il.com>, <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>, <ke.wang@...soc.com>, Matthew Wilcox <willy@...radead.org> Subject: Re: [Resend RFC PATCH] mm: introduce __GFP_TRACKLEAK to track in-kernel allocation Cc willy for page-flags changes. On Fri, 2 Sep 2022 18:59:07 +0800 "zhaoyang.huang" <zhaoyang.huang@...soc.com> wrote: > From: Zhaoyang Huang <zhaoyang.huang@...soc.com> > > 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. > > ... > cc wi > 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) We'd want this to evaluate to zero at compile time if CONFIG_HAVE_DEBUG_KMEMLEAK=n > 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) Please changelog this alteration. > 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) { And we'd want __GFP_TRACKLEAK to evaluate to zero at compile time if CONFIG_HAVE_DEBUG_KMEMLEAK=n. > + kmemleak_alloc(page_address(page), PAGE_SIZE << order, 1, gfp & ~__GFP_TRACKLEAK); > + __SetPageTrackleak(page); > + } > > trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype); > > -- > 1.9.1
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