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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pmdLm-0071m1-GL; Wed, 12 Apr 2023 16:29:38 +0000 Date: Wed, 12 Apr 2023 17:29:38 +0100 From: Matthew Wilcox To: Stefan Roesch Cc: kernel-team@fb.com, linux-mm@kvack.org, riel@surriel.com, mhocko@suse.com, david@redhat.com, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, akpm@linux-foundation.org, hannes@cmpxchg.org, Bagas Sanjaya Subject: Re: [PATCH v6 1/3] mm: add new api to enable ksm per process Message-ID: References: <20230412031648.2206875-1-shr@devkernel.io> <20230412031648.2206875-2-shr@devkernel.io> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: i6o6wsyu4ymryq9ouubs663sqig5gn94 X-Rspamd-Queue-Id: 7974FC000F X-HE-Tag: 1681316990-711722 X-HE-Meta: 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 DtMAdch6 F/1QmJRnB7ZR4/eswVAN4OTZ9CQX+b7ZFpBp8DbB4QC9d6pRNwrLqoQZ9G7fyrRii2Nu1oTqfgo6Hy3P55XkjhgVeEVgR5tUyhvoQmAI3Mw0q/NBDIJfdKTgeDF+oGedl+iGRvW1ZRyCNWhlrj2mYpiQG5E+yqnR1xiZHvFWD61qgZV0B6ms+3ps50O3oC3w9GGcHGW4eOEO1yZizQFo+6aNbbA== 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 Wed, Apr 12, 2023 at 09:08:11AM -0700, Stefan Roesch wrote: > > Matthew Wilcox writes: > > > On Tue, Apr 11, 2023 at 08:16:46PM -0700, Stefan Roesch wrote: > >> case PR_SET_VMA: > >> error = prctl_set_vma(arg2, arg3, arg4, arg5); > >> break; > >> +#ifdef CONFIG_KSM > >> + case PR_SET_MEMORY_MERGE: > >> + if (mmap_write_lock_killable(me->mm)) > >> + return -EINTR; > >> + > >> + if (arg2) { > >> + int err = ksm_add_mm(me->mm); > >> + > >> + if (!err) > >> + ksm_add_vmas(me->mm); > > > > in the last version of this patch, you reported the error. Now you > > swallow the error. I have no idea which is correct, but you've > > changed the behaviour without explaining it, so I assume it's wrong. > > > > I don't see how the error is swallowed in the arg2 case. If there is > an error ksm_add_vmas is not executedd and at the end of the function > the error is returned. Am I missing something? You said 'int err' which declares a new variable. If you want it reported, just use 'error = ksm_add_mm(me->mm);'.