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[209.85.220.65]) by mx.google.com with SMTPS id l9sor36704683iom.67.2019.07.26.14.10.29 for (Google Transport Security); Fri, 26 Jul 2019 14:10:29 -0700 (PDT) Received-SPF: pass (google.com: domain of alexander.duyck@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=J0efhXeS; spf=pass (google.com: domain of alexander.duyck@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=alexander.duyck@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=CnFsEo54QQCUj7cKXF+4BGmh5A92hzW17n6M7jlYUc0=; b=J0efhXeSqIUk7WkBdOyv4VzzdnTeBgFVPjWAZe5wML9pAmd1SbqhR4oq66HWtOqUJU 2712cWU2K32JLLUedtqpPz+8xMM2Wa+pMNGDyxeOs8f35KCXzq5SXBgjpc+JFQyskZVp A2y98FWuywv+ypUeMd0Dk5/2FbSSTdv/vkv2PxAB1Dp/djLa6qRapUKsRhQhbNVJGMUx HTgThLjpxOdu+6GthZrTfiIUagwZ0b/SKUru19GOCcdaAK/nLgXfJFZbzq92JvIXidX5 RJj4OpOG5GuTmNCqpQ9h0UkJGotM2gtIPpBiX88lkuV03qQ98felCFHcPBBA2Nm+gi1Z 59zw== X-Google-Smtp-Source: APXvYqwCY2wDc1hmXYnJZNoj6DLIuQys/RphK6WMSWlX/M3S6waa0t3YkBmQ3MMP1SIV4lt841KTJFqYoFyiTmFdjjA= X-Received: by 2002:a05:6602:2256:: with SMTP id o22mr3863805ioo.95.1564175429170; Fri, 26 Jul 2019 14:10:29 -0700 (PDT) MIME-Version: 1.0 References: <20190726210137.23395-1-willy@infradead.org> In-Reply-To: <20190726210137.23395-1-willy@infradead.org> From: Alexander Duyck Date: Fri, 26 Jul 2019 14:10:18 -0700 Message-ID: Subject: Re: [PATCH] mm: Make kvfree safe to call To: Matthew Wilcox Cc: Andrew Morton , linux-mm , LKML , Jeff Layton , Alexander Viro , Luis Henriques , Christoph Hellwig , Carlos Maiolino 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 Fri, Jul 26, 2019 at 2:01 PM Matthew Wilcox wrote: > > From: "Matthew Wilcox (Oracle)" > > Since vfree() can sleep, calling kvfree() from contexts where sleeping > is not permitted (eg holding a spinlock) is a bit of a lottery whether > it'll work. Introduce kvfree_safe() for situations where we know we can > sleep, but make kvfree() safe by default. > > Reported-by: Jeff Layton > Cc: Alexander Viro > Cc: Luis Henriques > Cc: Christoph Hellwig > Cc: Carlos Maiolino > Signed-off-by: Matthew Wilcox (Oracle) So you say you are adding kvfree_safe() in the patch description, but it looks like you are introducing kvfree_fast() below. Did something change and the patch description wasn't updated, or is this just the wrong description for this patch? > --- > mm/util.c | 26 ++++++++++++++++++++++++-- > 1 file changed, 24 insertions(+), 2 deletions(-) > > diff --git a/mm/util.c b/mm/util.c > index bab284d69c8c..992f0332dced 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -470,6 +470,28 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node) > } > EXPORT_SYMBOL(kvmalloc_node); > > +/** > + * kvfree_fast() - Free memory. > + * @addr: Pointer to allocated memory. > + * > + * kvfree_fast frees memory allocated by any of vmalloc(), kmalloc() or > + * kvmalloc(). It is slightly more efficient to use kfree() or vfree() if > + * you are certain that you know which one to use. > + * > + * Context: Either preemptible task context or not-NMI interrupt. Must not > + * hold a spinlock as it can sleep. > + */ > +void kvfree_fast(const void *addr) > +{ > + might_sleep(); > + > + if (is_vmalloc_addr(addr)) > + vfree(addr); > + else > + kfree(addr); > +} > +EXPORT_SYMBOL(kvfree_fast); > + > /** > * kvfree() - Free memory. > * @addr: Pointer to allocated memory. > @@ -478,12 +500,12 @@ EXPORT_SYMBOL(kvmalloc_node); > * It is slightly more efficient to use kfree() or vfree() if you are certain > * that you know which one to use. > * > - * Context: Either preemptible task context or not-NMI interrupt. > + * Context: Any context except NMI. > */ > void kvfree(const void *addr) > { > if (is_vmalloc_addr(addr)) > - vfree(addr); > + vfree_atomic(addr); > else > kfree(addr); > } > -- > 2.20.1 >