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b=LbOOrg6UPzlmVVhpLbmmBadHDKyaV6em4iZXtTw/bwi9OxEB/Z2kLznZZfoyaIpIn Pp63NWCW+s6iI/9BDWhG5OTJzxNYlVOrc8cF+gD4WtKa2p/hf1qgnWnVtiWqNzf25r iZ/hMM5i/iPJwr0aJr/ri1fXCtCP+bKeYXTCG272+P3vQquYYR5YJlJeTjnl/+2F3h JVnCBpNeX19CeVh6ic0bg7J1PiQCesrbEcvVJ3F9nt6uosWydyaCR9ACG9t7QYTqj3 ZP5uY/607EeWe/UU6/6jum7YQM3r6hPySVDYKrEMv1Ayk3Y5hEhQ0j+U3byptZjwG4 7vilOYdwoBoNg== Date: Wed, 3 Jun 2026 13:59:39 +0300 From: Mike Rapoport To: Lance Yang Cc: akpm@linux-foundation.org, david@kernel.org, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, luto@kernel.org, peterz@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, xueyuan.chen21@gmail.com, ioworker0@gmail.com Subject: Re: [RFC PATCH 1/2] mm/secretmem: try to restore large page mappings in direct map Message-ID: References: <20260603104624.36390-1-lance.yang@linux.dev> <20260603104624.36390-2-lance.yang@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260603104624.36390-2-lance.yang@linux.dev> X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: CB263120008 X-Stat-Signature: 8uwu94yw6jj71r99pwcwsoka4xi5tbrs X-HE-Tag: 1780484388-165860 X-HE-Meta: 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 REuXIqNO R5NgWLnhJDiEzs8trq3HCQaY4Q2x99mCpy9jQp1Ig7vwMBicEXZElegt9jEvsmmX03muR+P0ZVk6WTeWx7eh4ZUCCwUwEVX2tDpSRTaFBffMI0i0SduyRGePaBnyPWAnJkwwxCnFXrLKd+bcJErUk5zB48KM1fanHJkh4PCV5vgqZ6XjkMb7+vQTKoAoy747+o6e1eKhmouzw8veTvMxWuFrxFlGKnJMD8/gygjrZ6Jm9AP8Xy5ynm1BhgdnlJNhh33U4F2DXmc/TuMOsZFmEW4DdOO4JDCht2swWQwQLP684b8qTalZHtj7HtEBu9YA1ujIFkifIPOJoRN3PYhn0GUwHod/a43NeodXy Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Lance, On Wed, Jun 03, 2026 at 06:46:23PM +0800, Lance Yang wrote: > From: Lance Yang > > secretmem removes the pages backing secretmem mappings from the direct map. > > Removing one base page from the direct map can split the covering large > mapping down to PTE mappings. Repeated splits can leave more of the direct > map mapped with PTEs, meaning more TLB entries for the same range and > potentially more TLB pressure. > > So let's try to restore large page mappings whenever secretmem restores a > folio to the direct map. > > Tested-by: Xueyuan Chen > Signed-off-by: Lance Yang > --- > include/linux/set_memory.h | 6 ++++++ > mm/secretmem.c | 12 ++++++++++-- > 2 files changed, 16 insertions(+), 2 deletions(-) > > diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h > index 3030d9245f5a..ad2fa414a22d 100644 > --- a/include/linux/set_memory.h > +++ b/include/linux/set_memory.h > @@ -58,6 +58,12 @@ static inline bool can_set_direct_map(void) > #endif > #endif /* CONFIG_ARCH_HAS_SET_DIRECT_MAP */ > > +#ifndef arch_try_collapse_direct_map > +static inline void arch_try_collapse_direct_map(struct page *page) > +{ > +} > +#endif Did you explore what would it mean to hook collapse_large_pages() into set_direct_map_default_noflush()? -- Sincerely yours, Mike.