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Date:   Mon, 9 Oct 2023 19:24:03 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Lorenzo Stoakes <lstoakes@gmail.com>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Ian Rogers <irogers@google.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Oleg Nesterov <oleg@redhat.com>,
        Richard Cochran <richardcochran@gmail.com>,
        John Hubbard <jhubbard@nvidia.com>,
        Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH 4/4] mm/gup: adapt get_user_page_vma_remote() to never
 return NULL
Message-ID: <20231009222403.GE3952@nvidia.com>
References: <cover.1696174961.git.lstoakes@gmail.com>
 <b57d5f6618818f2f781a664039ace025c932074c.1696174961.git.lstoakes@gmail.com>
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On Sun, Oct 01, 2023 at 05:00:05PM +0100, Lorenzo Stoakes wrote:
> get_user_pages_remote() will never return 0 except in the case of
> FOLL_NOWAIT being specified, which we explicitly disallow.
> 
> This simplifies error handling for the caller and avoids the awkwardness of
> dealing with both errors and failing to pin. Failing to pin here is an
> error.
> 
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
> ---
>  arch/arm64/kernel/mte.c |  4 ++--
>  include/linux/mm.h      | 16 +++++++++++++---
>  kernel/events/uprobes.c |  4 ++--
>  mm/memory.c             |  3 +--
>  4 files changed, 18 insertions(+), 9 deletions(-)

Good riddance to IS_ERR_OR_NULL

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason