From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.3 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9958C43457 for ; Fri, 9 Oct 2020 07:16:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0A8DC2222F for ; Fri, 9 Oct 2020 07:16:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="G84d2ajc" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0A8DC2222F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 0FC4D6B005C; Fri, 9 Oct 2020 03:16:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0849E6B005D; Fri, 9 Oct 2020 03:16:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E8DC26B0062; Fri, 9 Oct 2020 03:16:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0030.hostedemail.com [216.40.44.30]) by kanga.kvack.org (Postfix) with ESMTP id BCF0B6B005C for ; Fri, 9 Oct 2020 03:16:54 -0400 (EDT) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 5D077362A for ; Fri, 9 Oct 2020 07:16:54 +0000 (UTC) X-FDA: 77351529948.09.brass37_1008f8f271de Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin09.hostedemail.com (Postfix) with ESMTP id 41124180AD804 for ; Fri, 9 Oct 2020 07:16:54 +0000 (UTC) X-HE-Tag: brass37_1008f8f271de X-Filterd-Recvd-Size: 11668 Received: from mail-ej1-f66.google.com (mail-ej1-f66.google.com [209.85.218.66]) by imf15.hostedemail.com (Postfix) with ESMTP for ; Fri, 9 Oct 2020 07:16:53 +0000 (UTC) Received: by mail-ej1-f66.google.com with SMTP id p15so11617034ejm.7 for ; Fri, 09 Oct 2020 00:16:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=reply-to:subject:to:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=5eq4Ar/6UjI/N5XgYhCiZtoWsUr9NhMRZnHycDLcVqI=; b=G84d2ajc/5uMkZModl3vF9kd2jBQx+D9/3pJHmM6Rgay42BhSZSAi31U2WRJZH2KfH z52u1UG6YpIzX+01kruZ6F14dUH60x97NqYO6/RXqjMN9IW1r1MAhjpuuC0lH6PRnGQf p93WPSqMgA+O7AkADGbSHICO9DdmliRWpL3kGEf5jJaus+/Y+TmmdP3DOuboz6XOaLWC dIt6PcWeE6JPM1U3hovXK65NAETmFjkGfurY+OhaPH6qRO4oRABK/I2buP7VvFgATM8o PlbvIZVwnTU/iUDDSx/DvZZ/f9nNAGBkeYbiGlkLTd3IBmZQUHytx2gqJBjyQhLxt1Yp KfSQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:reply-to:subject:to:references:from:message-id :date:user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=5eq4Ar/6UjI/N5XgYhCiZtoWsUr9NhMRZnHycDLcVqI=; b=guTI3Qw1UdCYEqDIKNVb0jyOafL3/T4IA/9gUeSICLKul5KR9A1yUulcsmUlgtDa14 15pDDgQnQfO5eBVIS+jy02yhuA131W7gqJLAPfOpURKN28orq+Ub9deZXdi+CtRaISFa +gnYnuLBClabN3kjcYwxPy9uFrBF40SSDF7b397KczvwdvVowDdCOypgL9n1sqtFOjCb BRzj7TD9m/WoaSdqQToUTbir4GhclkPwDD407XlFVsKIA0HtRqamNPzvgmsffOXA1ihc 8Z5QVzcP6D3E8dBb/c2jaTlgiuE6xdaibWAiZtdDzHKnR1lx4Z138LjoHZveBKh1gEat eXXA== X-Gm-Message-State: AOAM530pwW9ESZzXEI8SjSuZ97mOpJx1Z+npOvci7n5t//tEzKhgOmRy duOlmi+NdmsLDU0zTG8hpWA= X-Google-Smtp-Source: ABdhPJzpHKRuaxXV0iNYwD99THWlH6duPzIzfXxWGfzb72nTC+0HwpHy6g25AB7SG0/yyyLEpqBgrA== X-Received: by 2002:a17:906:4e16:: with SMTP id z22mr6743173eju.527.1602227812229; Fri, 09 Oct 2020 00:16:52 -0700 (PDT) Received: from ?IPv6:2a02:908:1252:fb60:be8a:bd56:1f94:86e7? ([2a02:908:1252:fb60:be8a:bd56:1f94:86e7]) by smtp.gmail.com with ESMTPSA id gv10sm5795761ejb.46.2020.10.09.00.16.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 09 Oct 2020 00:16:51 -0700 (PDT) Reply-To: christian.koenig@amd.com Subject: Re: [PATCH 1/4] mm: introduce vma_set_file function v2 To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linaro-mm-sig@lists.linaro.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, chris@chris-wilson.co.uk, airlied@redhat.com, akpm@linux-foundation.org, sumit.semwal@linaro.org References: <20201008112342.9394-1-christian.koenig@amd.com> <20201008141211.GG438822@phenom.ffwll.local> From: =?UTF-8?Q?Christian_K=c3=b6nig?= Message-ID: <8fc28dfa-4bae-bee1-5aca-4e3c6e88b994@gmail.com> Date: Fri, 9 Oct 2020 09:16:49 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201008141211.GG438822@phenom.ffwll.local> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable 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: Am 08.10.20 um 16:12 schrieb Daniel Vetter: > On Thu, Oct 08, 2020 at 01:23:39PM +0200, Christian K=C3=B6nig wrote: >> Add the new vma_set_file() function to allow changing >> vma->vm_file with the necessary refcount dance. >> >> v2: add more users of this. >> >> Signed-off-by: Christian K=C3=B6nig >> --- >> drivers/dma-buf/dma-buf.c | 16 +++++----------- >> drivers/gpu/drm/etnaviv/etnaviv_gem.c | 4 +--- >> drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 3 +-- >> drivers/gpu/drm/i915/gem/i915_gem_mman.c | 4 ++-- >> drivers/gpu/drm/msm/msm_gem.c | 4 +--- >> drivers/gpu/drm/omapdrm/omap_gem.c | 3 +-- >> drivers/gpu/drm/vgem/vgem_drv.c | 3 +-- >> drivers/staging/android/ashmem.c | 5 ++--- >> include/linux/mm.h | 2 ++ >> mm/mmap.c | 16 ++++++++++++++++ >> 10 files changed, 32 insertions(+), 28 deletions(-) >> >> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c >> index a6ba4d598f0e..e4316aa7e0f4 100644 >> --- a/drivers/dma-buf/dma-buf.c >> +++ b/drivers/dma-buf/dma-buf.c >> @@ -1163,20 +1163,14 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struc= t vm_area_struct *vma, >> return -EINVAL; >> =20 >> /* readjust the vma */ >> - get_file(dmabuf->file); >> - oldfile =3D vma->vm_file; >> - vma->vm_file =3D dmabuf->file; >> + oldfile =3D vma_set_file(vma, dmabuf->file); >> vma->vm_pgoff =3D pgoff; >> =20 >> ret =3D dmabuf->ops->mmap(dmabuf, vma); >> - if (ret) { >> - /* restore old parameters on failure */ >> - vma->vm_file =3D oldfile; >> - fput(dmabuf->file); >> - } else { >> - if (oldfile) >> - fput(oldfile); >> - } >> + /* restore old parameters on failure */ >> + if (ret) >> + vma_set_file(vma, oldfile); > I think these two lines here are cargo-cult: If this fails, the mmap fa= ils > and therefore the vma structure is kfreed. No point at all in restoring > anything. This was explicitly added with this patch to fix a problem: commit 495c10cc1c0c359871d5bef32dd173252fc17995 Author: John Sheu Date:=C2=A0=C2=A0 Mon Feb 11 17:50:24 2013 -0800 =C2=A0=C2=A0=C2=A0 CHROMIUM: dma-buf: restore args on failure of dma_buf= _mmap =C2=A0=C2=A0=C2=A0 Callers to dma_buf_mmap expect to fput() the vma stru= ct's vm_file =C2=A0=C2=A0=C2=A0 themselves on failure.=C2=A0 Not restoring the struct= 's data on failure =C2=A0=C2=A0=C2=A0 causes a double-decrement of the vm_file's refcount. > With that: Reviewed-by: Daniel Vetter Can I keep that even with the error handling working? :) Christian. > >> + >> return ret; >> =20 >> } >> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/e= tnaviv/etnaviv_gem.c >> index 312e9d58d5a7..10ce267c0947 100644 >> --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c >> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c >> @@ -145,10 +145,8 @@ static int etnaviv_gem_mmap_obj(struct etnaviv_ge= m_object *etnaviv_obj, >> * address_space (so unmap_mapping_range does what we want, >> * in particular in the case of mmap'd dmabufs) >> */ >> - fput(vma->vm_file); >> - get_file(etnaviv_obj->base.filp); >> vma->vm_pgoff =3D 0; >> - vma->vm_file =3D etnaviv_obj->base.filp; >> + vma_set_file(vma, etnaviv_obj->base.filp); >> =20 >> vma->vm_page_prot =3D vm_page_prot; >> } >> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/= drm/i915/gem/i915_gem_dmabuf.c >> index fec0e1e3dc3e..8ce4c9e28b87 100644 >> --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >> @@ -119,8 +119,7 @@ static int i915_gem_dmabuf_mmap(struct dma_buf *dm= a_buf, struct vm_area_struct * >> if (ret) >> return ret; >> =20 >> - fput(vma->vm_file); >> - vma->vm_file =3D get_file(obj->base.filp); >> + vma_set_file(vma, obj->base.filp); >> =20 >> return 0; >> } >> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/dr= m/i915/gem/i915_gem_mman.c >> index 3d69e51f3e4d..c9d5f1a38af3 100644 >> --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c >> @@ -893,8 +893,8 @@ int i915_gem_mmap(struct file *filp, struct vm_are= a_struct *vma) >> * requires avoiding extraneous references to their filp, hence why >> * we prefer to use an anonymous file for their mmaps. >> */ >> - fput(vma->vm_file); >> - vma->vm_file =3D anon; >> + vma_set_file(vma, anon); >> + fput(anon); >> =20 >> switch (mmo->mmap_type) { >> case I915_MMAP_TYPE_WC: >> diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_g= em.c >> index de915ff6f4b4..a71f42870d5e 100644 >> --- a/drivers/gpu/drm/msm/msm_gem.c >> +++ b/drivers/gpu/drm/msm/msm_gem.c >> @@ -223,10 +223,8 @@ int msm_gem_mmap_obj(struct drm_gem_object *obj, >> * address_space (so unmap_mapping_range does what we want, >> * in particular in the case of mmap'd dmabufs) >> */ >> - fput(vma->vm_file); >> - get_file(obj->filp); >> vma->vm_pgoff =3D 0; >> - vma->vm_file =3D obj->filp; >> + vma_set_file(vma, obj->filp); >> =20 >> vma->vm_page_prot =3D vm_get_page_prot(vma->vm_flags); >> } >> diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omap= drm/omap_gem.c >> index 979d53a93c2b..0d4542ff1d7d 100644 >> --- a/drivers/gpu/drm/omapdrm/omap_gem.c >> +++ b/drivers/gpu/drm/omapdrm/omap_gem.c >> @@ -564,9 +564,8 @@ int omap_gem_mmap_obj(struct drm_gem_object *obj, >> * address_space (so unmap_mapping_range does what we want, >> * in particular in the case of mmap'd dmabufs) >> */ >> - fput(vma->vm_file); >> vma->vm_pgoff =3D 0; >> - vma->vm_file =3D get_file(obj->filp); >> + vma_set_file(vma, obj->filp); >> =20 >> vma->vm_page_prot =3D vm_get_page_prot(vma->vm_flags); >> } >> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vg= em_drv.c >> index fa54a6d1403d..ea0eecae5153 100644 >> --- a/drivers/gpu/drm/vgem/vgem_drv.c >> +++ b/drivers/gpu/drm/vgem/vgem_drv.c >> @@ -397,8 +397,7 @@ static int vgem_prime_mmap(struct drm_gem_object *= obj, >> if (ret) >> return ret; >> =20 >> - fput(vma->vm_file); >> - vma->vm_file =3D get_file(obj->filp); >> + vma_set_file(vma, obj->filp); >> vma->vm_flags |=3D VM_DONTEXPAND | VM_DONTDUMP; >> vma->vm_page_prot =3D pgprot_writecombine(vm_get_page_prot(vma->vm_= flags)); >> =20 >> diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/androi= d/ashmem.c >> index 10b4be1f3e78..a51dc089896e 100644 >> --- a/drivers/staging/android/ashmem.c >> +++ b/drivers/staging/android/ashmem.c >> @@ -450,9 +450,8 @@ static int ashmem_mmap(struct file *file, struct v= m_area_struct *vma) >> vma_set_anonymous(vma); >> } >> =20 >> - if (vma->vm_file) >> - fput(vma->vm_file); >> - vma->vm_file =3D asma->file; >> + vma_set_file(vma, asma->file); >> + fput(asma->file); >> =20 >> out: >> mutex_unlock(&ashmem_mutex); >> diff --git a/include/linux/mm.h b/include/linux/mm.h >> index ca6e6a81576b..a558602afe1b 100644 >> --- a/include/linux/mm.h >> +++ b/include/linux/mm.h >> @@ -2693,6 +2693,8 @@ static inline void vma_set_page_prot(struct vm_a= rea_struct *vma) >> } >> #endif >> =20 >> +struct file *vma_set_file(struct vm_area_struct *vma, struct file *fi= le); >> + >> #ifdef CONFIG_NUMA_BALANCING >> unsigned long change_prot_numa(struct vm_area_struct *vma, >> unsigned long start, unsigned long end); >> diff --git a/mm/mmap.c b/mm/mmap.c >> index 40248d84ad5f..d3c3c510f643 100644 >> --- a/mm/mmap.c >> +++ b/mm/mmap.c >> @@ -136,6 +136,22 @@ void vma_set_page_prot(struct vm_area_struct *vma= ) >> WRITE_ONCE(vma->vm_page_prot, vm_page_prot); >> } >> =20 >> +/* >> + * Change backing file, only valid to use during initial VMA setup. >> + */ >> +struct file *vma_set_file(struct vm_area_struct *vma, struct file *fi= le) >> +{ >> + if (file) >> + get_file(file); >> + >> + swap(vma->vm_file, file); >> + >> + if (file) >> + fput(file); >> + >> + return file; >> +} >> + >> /* >> * Requires inode->i_mapping->i_mmap_rwsem >> */ >> --=20 >> 2.17.1 >>