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[70.27.3.10]) by smtp.gmail.com with ESMTPSA id bk22-20020a05620a1a1600b006b9c9b7db8bsm12167528qkb.82.2022.09.06.12.39.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Sep 2022 12:39:54 -0700 (PDT) Date: Tue, 6 Sep 2022 15:39:51 -0400 From: Peter Xu To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, paulmck@kernel.org, luto@kernel.org, songliubraving@fb.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, kernel-team@android.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH RESEND 19/28] mm: disallow do_swap_page to handle page faults under VMA lock Message-ID: References: <20220901173516.702122-1-surenb@google.com> <20220901173516.702122-20-surenb@google.com> MIME-Version: 1.0 In-Reply-To: <20220901173516.702122-20-surenb@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662493198; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ipDmQ48fSdnKUDgmzFqHXYya44lh/1wuhiABbNwvM7Y=; b=eTYUCzp3LDrXXYvJK+Cx2lLD6DkTPkkwP4oyR5iZgFubkwQIpk8UHDKGucHu2EXrEJD7y1 wzsy0iEM28lhd2vOHIHW/7fwMlKJueIYtMwbX9MfZOdN+zZqqJYZKr9FNqwwoPEWLjDex4 f5zAbeO7mZiWyJsqY3oWNtMxD5ebMuI= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=fkVb6eK7; spf=pass (imf01.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662493198; a=rsa-sha256; cv=none; b=GMtsE2NOSb1VOwF116REs3j877qpxGIrOFrTiserBRDTfrwMU2ChfztUHkSV3WoDxf8Tr/ 37JAooLr0RSnTRrd1aJLis534orkV5iCGDak+Jz1OeTrY00jEsxhaqGDNq0lQQ/qEgkjEk L16lmQG/Az7fSZ7mzH6qLeicOoTpfK0= X-Stat-Signature: eg54mu3ffmfn4tmx8bkju5knh7m4m43j X-Rspamd-Queue-Id: 98D214006A X-Rspam-User: Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=fkVb6eK7; spf=pass (imf01.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Rspamd-Server: rspam03 X-HE-Tag: 1662493197-704264 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, Sep 01, 2022 at 10:35:07AM -0700, Suren Baghdasaryan wrote: > Due to the possibility of do_swap_page dropping mmap_lock, abort fault > handling under VMA lock and retry holding mmap_lock. This can be handled > more gracefully in the future. > > Signed-off-by: Suren Baghdasaryan > --- > mm/memory.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/mm/memory.c b/mm/memory.c > index 9ac9944e8c62..29d2f49f922a 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3738,6 +3738,11 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > vm_fault_t ret = 0; > void *shadow = NULL; > > + if (vmf->flags & FAULT_FLAG_VMA_LOCK) { > + ret = VM_FAULT_RETRY; > + goto out; > + } > + May want to fail early similarly for handle_userfault() too for similar reason. Thanks, -- Peter Xu