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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id e7sm3507003otp.64.2019.09.09.23.27.54 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 09 Sep 2019 23:27:55 -0700 (PDT) Date: Mon, 9 Sep 2019 23:27:15 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Al Viro cc: Hugh Dickins , kernel test robot , David Howells , Andrew Morton , LKML , linux-fsdevel@vger.kernel.org, lkp@01.org Subject: Re: [vfs] 8bb3c61baf: vm-scalability.median -23.7% regression In-Reply-To: <20190909035653.GF1131@ZenIV.linux.org.uk> Message-ID: References: <20190903084122.GH15734@shao2-debian> <20190908214601.GC1131@ZenIV.linux.org.uk> <20190908234722.GE1131@ZenIV.linux.org.uk> <20190909035653.GF1131@ZenIV.linux.org.uk> User-Agent: Alpine 2.11 (LSU 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 9 Sep 2019, Al Viro wrote: > > Anyway, see vfs.git#uncertain.shmem for what I've got with those folded in. > Do you see any problems with that one? That's the last 5 commits in there... It's mostly fine, I've no problem with going your way instead of what we had in mmotm; but I have seen some problems with it, and had been intending to send you a fixup patch tonight (shmem_reconfigure() missing unlock on error is the main problem, but there are other fixes needed). But I'm growing tired. I've a feeling my "swap" of the mpols, instead of immediate mpol_put(), was necessary to protect against a race with shmem_get_sbmpol(), but I'm not clear-headed enough to trust myself on that now. And I've a mystery to solve, that shmem_reconfigure() gets stuck into showing the wrong error message. Tomorrow.... Oh, and my first attempt to build and boot that series over 5.3-rc5 wouldn't boot. Luckily there was a tell-tale "i915" in the stacktrace, which reminded me of the drivers/gpu/drm/i915/gem/i915_gemfs.c fix we discussed earlier in the cycle. That is of course in linux-next by now, but I wonder if your branch ought to contain a duplicate of that fix, so that people with i915 doing bisections on 5.4-rc do not fall into an unbootable hole between vfs and gpu merges. Hugh