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Shutemov" , Lorenzo Stoakes , Uladzislau Rezki , Zi Yan , linux-kernel@vger.kernel.org, linux-mm@kvack.org, damon@lists.linux.dev Subject: Re: [PATCH v2 3/5] mm: Fix failure to unmap pte on highmem systems Message-ID: <20230524185949.GQ4967@kernel.org> References: <20230518110727.2106156-1-ryan.roberts@arm.com> <20230518110727.2106156-4-ryan.roberts@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230518110727.2106156-4-ryan.roberts@arm.com> X-Rspamd-Queue-Id: A6A2440025 X-Rspam-User: X-Stat-Signature: sxyypy6qdgk17jrmek16kfyzd98ogcxo X-Rspamd-Server: rspam01 X-HE-Tag: 1684954813-287944 X-HE-Meta: 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 LB4lK7IK pgprxYwM5WF/zQ3Ja9TRkDIiYT37lAWgJQqRdRZOKvvlWwemZ0daJZ0fZoYPTrswPL0vH06q6SeZZIT4fuZVrv8v0upiLCLF30NLpgch4B92kTHazdP7cH2pyZuqQxy+szrOSGcG86za74U4av77v083qFUVk0smB+nHhFgjguGJk+SteZJt++4eSKa6zkMRcNKoh/NJdcXZkk0yWzZ8lVYrsPLpn+T+38G8c0qj0uCM1gJzRqXF+/Dv1GeR6rCspTD9LmgbJRvE/ZHKvatfULceROWUPN/5ndIyU03FKAVk4Hb4rblDg0v5r47xFuHpC1Ospz9K5yAQ8jUREZtG4rNNB/nbTcaJbM6CSThObFPP6PiVLLI0qKQXx0MSFg9i6VZi4N3VdwdgR6Z3X8y0C1ONvm1YCk1BxD0srKIcqwPsYLuWgOPz002SExw== 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 Thu, May 18, 2023 at 12:07:25PM +0100, Ryan Roberts wrote: > The loser of a race to service a pte for a device private entry in the > swap path previously unlocked the ptl, but failed to unmap the pte. This > only affects highmem systems since unmapping a pte is a noop on > non-highmem systems. > > Fixes: 16ce101db85d ("mm/memory.c: fix race when faulting a device private page") > Signed-off-by: Ryan Roberts > Reviewed-by: Zi Yan Reviewed-by: Mike Rapoport (IBM) > --- > mm/memory.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index f69fbc251198..ed429e20a1bb 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3728,10 +3728,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > vmf->page = pfn_swap_entry_to_page(entry); > vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, > vmf->address, &vmf->ptl); > - if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) { > - spin_unlock(vmf->ptl); > - goto out; > - } > + if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) > + goto unlock; > > /* > * Get a page reference while we know the page can't be > -- > 2.25.1 > > -- Sincerely yours, Mike.