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[209.85.220.65]) by mx.google.com with SMTPS id a8sor1007372ywh.64.2019.07.16.14.20.40 for (Google Transport Security); Tue, 16 Jul 2019 14:20:40 -0700 (PDT) Received-SPF: pass (google.com: domain of shakeelb@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=mzkioEkQ; spf=pass (google.com: domain of shakeelb@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=shakeelb@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=JJ9YJBDa6TAoDZnqGKrJ33E8HHSw9cbft8xMZfhrH5o=; b=mzkioEkQusJ5+fSK27pN+Vp0ac4Y/hSwdtz9EBb/CGG+fQfnQpfNVJ4Nrn//Qzq2Sm ylEq8N1PhAUCbcJRX7iDYz/lqELXX2RiXjjyA9ljx3qmwq0sONvfWl06a0Mn5ntJGU6S HM8qXNVmfSIdYce6w4BJPgEs8i9O3VairrVzwHC66pvik4T4SSVAO2jeohAOuANIq7P5 cOsnhIMLJ526MbaDy6UjqAUEBr5hfXPe3Pucn/DrRLtbgSOnYK2+TE+ycQrWwf/kwoyM viQZLFx2ns8ebYgjZTz5eJCXtIgbh8+iMOJJfoPte0qOVJWIBE8ftoyCOtoXBRrl1p2k qiPw== X-Google-Smtp-Source: APXvYqxIk0Kusbyfed606KNi4eGPzY+cdM8lYWMrMR8rMZ/4PdfezbgsydDu8UR4zXJIqhguZ5+jeBmCzF6RdAVtQ7s= X-Received: by 2002:a0d:cb42:: with SMTP id n63mr21966936ywd.205.1563312039498; Tue, 16 Jul 2019 14:20:39 -0700 (PDT) MIME-Version: 1.0 References: <20190716000520.230595-1-henryburns@google.com> In-Reply-To: <20190716000520.230595-1-henryburns@google.com> From: Shakeel Butt Date: Tue, 16 Jul 2019 14:20:28 -0700 Message-ID: Subject: Re: [PATCH v2] mm/z3fold.c: Reinitialize zhdr structs after migration To: Henry Burns Cc: Vitaly Vul , Andrew Morton , Jonathan Adams , Linux MM , LKML Content-Type: text/plain; charset="UTF-8" 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 Mon, Jul 15, 2019 at 5:05 PM Henry Burns wrote: > > z3fold_page_migration() calls memcpy(new_zhdr, zhdr, PAGE_SIZE). > However, zhdr contains fields that can't be directly coppied over (ex: > list_head, a circular linked list). We only need to initialize the > linked lists in new_zhdr, as z3fold_isolate_page() already ensures > that these lists are empty > > Additionally it is possible that zhdr->work has been placed in a > workqueue. In this case we shouldn't migrate the page, as zhdr->work > references zhdr as opposed to new_zhdr. > > Fixes: bba4c5f96ce4 ("mm/z3fold.c: support page migration") > Signed-off-by: Henry Burns Reviewed-by: Shakeel Butt > --- > Changelog since v1: > - Made comments explicityly refer to new_zhdr->buddy. > > mm/z3fold.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/mm/z3fold.c b/mm/z3fold.c > index 42ef9955117c..f4b2283b19a3 100644 > --- a/mm/z3fold.c > +++ b/mm/z3fold.c > @@ -1352,12 +1352,22 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa > z3fold_page_unlock(zhdr); > return -EBUSY; > } > + if (work_pending(&zhdr->work)) { > + z3fold_page_unlock(zhdr); > + return -EAGAIN; > + } > new_zhdr = page_address(newpage); > memcpy(new_zhdr, zhdr, PAGE_SIZE); > newpage->private = page->private; > page->private = 0; > z3fold_page_unlock(zhdr); > spin_lock_init(&new_zhdr->page_lock); > + INIT_WORK(&new_zhdr->work, compact_page_work); > + /* > + * z3fold_page_isolate() ensures that new_zhdr->buddy is empty, > + * so we only have to reinitialize it. > + */ > + INIT_LIST_HEAD(&new_zhdr->buddy); > new_mapping = page_mapping(page); > __ClearPageMovable(page); > ClearPagePrivate(page); > -- > 2.22.0.510.g264f2c817a-goog >