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Message-ID: <7733852a-67c9-17a3-4031-cb08520b9ad2@huawei.com> Date: Mon, 7 Aug 2017 14:26:21 +0300 From: Igor Stoppa <igor.stoppa@...wei.com> To: Michal Hocko <mhocko@...nel.org> CC: Jerome Glisse <jglisse@...hat.com>, Linux-MM <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>, <linux-security-module@...r.kernel.org>, "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, Kees Cook <keescook@...gle.com> Subject: Re: [RFC] Tagging of vmalloc pages for supporting the pmalloc allocator On 04/08/17 11:12, Michal Hocko wrote: > On Fri 04-08-17 11:02:46, Igor Stoppa wrote: [...] >> struct page { >> /* First double word block */ >> unsigned long flags; /* Atomic flags, some possibly >> * updated asynchronously */ >> union { >> struct address_space *mapping; /* If low bit clear, points to >> * inode address_space, or NULL. >> * If page mapped as anonymous >> * memory, low bit is set, and >> * it points to anon_vma object: >> * see PAGE_MAPPING_ANON below. >> */ >> ... >> } >> >> mapping seems to be used exclusively in 2 ways, based on the value of >> its lower bit. > > Not really. The above applies to LRU pages. Please note that Slab pages > use s_mem and huge pages use compound_mapcount. If vmalloc pages are > using none of those already you can add a new field there. Yes, both from reading the code and some experimentation, it seems that vmalloc is not using either field. I'll add a vm_area field as you advised. Is this something I could send as standalone patch? -- thank you, igor
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