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Tue, 16 May 2023 19:21:57 -0700 (PDT) MIME-Version: 1.0 References: <20230516023514.2643054-1-pcc@google.com> <20230516023514.2643054-2-pcc@google.com> <342d76b0-a94f-902a-c701-04a1e477b748@redhat.com> In-Reply-To: <342d76b0-a94f-902a-c701-04a1e477b748@redhat.com> From: Peter Collingbourne Date: Tue, 16 May 2023 19:21:46 -0700 Message-ID: Subject: Re: [PATCH v2 1/2] mm: Call arch_swap_restore() from do_swap_page() To: David Hildenbrand Cc: Catalin Marinas , =?UTF-8?B?UXVuLXdlaSBMaW4gKOael+e+pOW0tCk=?= , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "surenb@google.com" , =?UTF-8?B?Q2hpbndlbiBDaGFuZyAo5by16Yym5paHKQ==?= , "kasan-dev@googlegroups.com" , =?UTF-8?B?S3Vhbi1ZaW5nIExlZSAo5p2O5Yag56mOKQ==?= , =?UTF-8?B?Q2FzcGVyIExpICjmnY7kuK3mpq4p?= , "gregkh@linuxfoundation.org" , vincenzo.frascino@arm.com, Alexandru Elisei , will@kernel.org, eugenis@google.com, Steven Price , stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: yzusks5bi9t8se1bn4dsnjyho7kuwnat X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: D9D7E40007 X-Rspam-User: X-HE-Tag: 1684290118-698553 X-HE-Meta: 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 2LtrDN0M 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 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 Tue, May 16, 2023 at 5:49=E2=80=AFAM David Hildenbrand wrote: > > On 16.05.23 04:35, Peter Collingbourne wrote: > > Commit c145e0b47c77 ("mm: streamline COW logic in do_swap_page()") move= d > > the call to swap_free() before the call to set_pte_at(), which meant th= at > > the MTE tags could end up being freed before set_pte_at() had a chance > > to restore them. Fix it by adding a call to the arch_swap_restore() hoo= k > > before the call to swap_free(). > > > > Signed-off-by: Peter Collingbourne > > Link: https://linux-review.googlesource.com/id/I6470efa669e8bd2f841049b= 8c61020c510678965 > > Cc: # 6.1 > > Fixes: c145e0b47c77 ("mm: streamline COW logic in do_swap_page()") > > Reported-by: Qun-wei Lin (=E6=9E=97=E7=BE=A4=E5=B4=B4) > > Link: https://lore.kernel.org/all/5050805753ac469e8d727c797c2218a9d780d= 434.camel@mediatek.com/ > > --- > > v2: > > - Call arch_swap_restore() directly instead of via arch_do_swap_page() > > > > mm/memory.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/mm/memory.c b/mm/memory.c > > index 01a23ad48a04..a2d9e6952d31 100644 > > --- a/mm/memory.c > > +++ b/mm/memory.c > > @@ -3914,6 +3914,13 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > > } > > } > > > > + /* > > + * Some architectures may have to restore extra metadata to the p= age > > + * when reading from swap. This metadata may be indexed by swap e= ntry > > + * so this must be called before swap_free(). > > + */ > > + arch_swap_restore(entry, folio); > > + > > /* > > * Remove the swap entry and conditionally try to free up the swa= pcache. > > * We're already holding a reference on the page but haven't mapp= ed it > > Looks much better to me, thanks :) > > ... staring at unuse_pte(), I suspect it also doesn't take care of MTE > tags and needs fixing? Nice catch, I've fixed it in v3. I don't think there are any other cases like this. I looked for code that decrements the MM_SWAPENTS counter and we're already covering all of them. Peter