From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f169.google.com (mail-pf1-f169.google.com [209.85.210.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 94D8529CA for ; Fri, 10 Dec 2021 10:44:41 +0000 (UTC) Received: by mail-pf1-f169.google.com with SMTP id i12so8118781pfd.6 for ; Fri, 10 Dec 2021 02:44:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=0U8OtES5xOj4rqgnd2vdl4trSth3+050XfcObSQBQ58=; b=KdTmk3w7bmfzFk7lnwFxJUX4SzMf3YcvWLIvC/3KqTNvA5BCm0daDjN3XEP6tgr7fb qJjxeZl124cLQYufEByAOcgi0jlWmxl6OcxSZnUb5tFw8GjHStsxjMSpDJDLBosZlvcn k5ccAPIPdlLcRdBsMTP24plm4wRRaz6KbMps78pA97TBZZORbaNq03FkbgfYh7pxintc sBQ/WeMhcxm2X+ePjadP7N0yvevNjQ3RLL2SI4gPkls80c+gzF0VgYk7+K3bmTMjjUHY wIK4ChK9Lnu4OO611jbVCsnDVx0Ua41VaJ9bTccQej13+aiQFv41U8rB0k2zbi+Wvtr7 h8Gw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=0U8OtES5xOj4rqgnd2vdl4trSth3+050XfcObSQBQ58=; b=XQQucOhESSH0KFlJ26adbAce1f37zVD4XSS7/ThpkR5hz/yL7F1dokyLYhuEVS/5ce 02YrvBZOsarFjDQa4LMlP9gcYbfUKHfuvCBEq4b4V2p4qOr9NXN/F8a+TlZx2pMBc4zm 5gXgwKkdGI4diosZqOlW1/SlFVxy8eJ01tS24ZCPHWA6Fp9dT+Psr741nDiPCbh4VGmE 79EYf+EuYjUs6jrLckmziFSfEQ1/rdirp7FlfwZp8vkza9e3pleLP2n7hbEJ80W9cvPQ /x+GCAt3GOpAMKaNpWn5s2PFS/Xpv0Y+UJZSg7pc1Y0zu+rQi18ZEwhus+Jn7obLt5RW otQg== X-Gm-Message-State: AOAM530Vhc9ePFRTCh9gfPUuX5gG57uyFOPXHONLDe1Vc9Fpi2wqTH2O Fn8h3jpNf21m2uJkJoEzIMc= X-Google-Smtp-Source: ABdhPJyll9nMQuRPwgwMd9dUKhLY1En8Eimub3NMYDOH6MCdrfAGbhcNGJjptNiCGNdOecDZaxA/Xw== X-Received: by 2002:a63:6987:: with SMTP id e129mr38676747pgc.520.1639133081071; Fri, 10 Dec 2021 02:44:41 -0800 (PST) Received: from odroid ([114.29.23.242]) by smtp.gmail.com with ESMTPSA id 16sm2264896pgu.93.2021.12.10.02.44.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Dec 2021 02:44:40 -0800 (PST) Date: Fri, 10 Dec 2021 10:44:35 +0000 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Vlastimil Babka Cc: Matthew Wilcox , Christoph Lameter , David Rientjes , Joonsoo Kim , Pekka Enberg , linux-mm@kvack.org, Andrew Morton , patches@lists.linux.dev Subject: Re: [PATCH v2 24/33] mm/slob: Convert SLOB to use struct slab Message-ID: <20211210104435.GA632117@odroid> References: <20211201181510.18784-1-vbabka@suse.cz> <20211201181510.18784-25-vbabka@suse.cz> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211201181510.18784-25-vbabka@suse.cz> On Wed, Dec 01, 2021 at 07:15:01PM +0100, Vlastimil Babka wrote: > From: "Matthew Wilcox (Oracle)" > > Use struct slab throughout the slob allocator. > > [ vbabka@suse.cz: don't introduce wrappers for PageSlobFree in mm/slab.h just > for the single callers being wrappers in mm/slob.c ] > > Signed-off-by: Matthew Wilcox (Oracle) > Signed-off-by: Vlastimil Babka > --- > mm/slob.c | 34 +++++++++++++++++----------------- > 1 file changed, 17 insertions(+), 17 deletions(-) > > diff --git a/mm/slob.c b/mm/slob.c > index d2d15e7f191c..d3512bcc3141 100644 > --- a/mm/slob.c > +++ b/mm/slob.c ... > /* Enough room on this page? */ > @@ -358,8 +358,8 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node, > b = slob_new_pages(gfp & ~__GFP_ZERO, 0, node); > if (!b) > return NULL; > - sp = virt_to_page(b); > - __SetPageSlab(sp); > + sp = virt_to_slab(b); > + __SetPageSlab(slab_page(sp)); Hello Vlastimil. I've tested this patch on my machine and it causes NULL pointer dereference. that's because virt_to_slab returns NULL if folio_test_slab is false. and __SetPageSlab is called with sp = NULL. diff below fixed bug. diff --git a/mm/slob.c b/mm/slob.c index d3512bcc3141..cf669f03440f 100644 --- a/mm/slob.c +++ b/mm/slob.c @@ -358,8 +358,8 @@ static void *slob_alloc(size_t size, gfp_t gfp, int a lign, int node, b = slob_new_pages(gfp & ~__GFP_ZERO, 0, node); if (!b) return NULL; + __SetPageSlab(virt_to_page(b)); sp = virt_to_slab(b); - __SetPageSlab(slab_page(sp)); spin_lock_irqsave(&slob_lock, flags); sp->units = SLOB_UNITS(PAGE_SIZE); Thanks, Hyeonggon. > > spin_lock_irqsave(&slob_lock, flags); > sp->units = SLOB_UNITS(PAGE_SIZE); > @@ -381,7 +381,7 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node, > */ > static void slob_free(void *block, int size) > { > - struct page *sp; > + struct slab *sp; > slob_t *prev, *next, *b = (slob_t *)block; > slobidx_t units; > unsigned long flags; > @@ -391,7 +391,7 @@ static void slob_free(void *block, int size) > return; > BUG_ON(!size); > > - sp = virt_to_page(block); > + sp = virt_to_slab(block); > units = SLOB_UNITS(size); > > spin_lock_irqsave(&slob_lock, flags); > @@ -401,8 +401,8 @@ static void slob_free(void *block, int size) > if (slob_page_free(sp)) > clear_slob_page_free(sp); > spin_unlock_irqrestore(&slob_lock, flags); > - __ClearPageSlab(sp); > - page_mapcount_reset(sp); > + __ClearPageSlab(slab_page(sp)); > + page_mapcount_reset(slab_page(sp)); > slob_free_pages(b, 0); > return; > } > -- > 2.33.1 > >