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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Ui0+1jMzj/HFyPwLgMd+uu8A17z2Fo19bUnzQ5WOHpHIC0Jrw9bc5Tc/l2+1wFYSM NyY8mzr1NED4iwaPd1f2p1sF/Y9r+rk9+M3NOG6S23iLNBA2sL7TdnAtF4wS4uLCV2 ydynjooP7qcvFNkL+EivMXciyB0dfeGzBeCgkWzA= Message-ID: <8cc0b340-9526-47ac-abd4-3f5724963409@arm.com> Date: Tue, 8 Sep 2026 11:08:13 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 5/8] mm/internal: rename swap offset helpers to softleaf offset To: Barry Song Cc: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, hughd@google.com, chrisl@kernel.org, kasong@tencent.com, riel@surriel.com, liam@infradead.org, vbabka@kernel.org, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, baolin.wang@linux.alibaba.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, baoquan.he@linux.dev, youngjun.park@lge.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, pfalcato@suse.de, ryan.roberts@arm.com, anshuman.khandual@arm.com References: <20260901054358.4049095-1-dev.jain@arm.com> <20260901054358.4049095-6-dev.jain@arm.com> <12efdc7f-ff82-412b-b79d-bff211d34218@arm.com> Content-Language: en-US From: Dev Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: jskw5a4pf83ujxkkaeisq8qs9nqua8rf X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 205BE100002 X-Rspam-User: X-HE-Tag: 1788845901-689065 X-HE-Meta: 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 gL/pSWI8 ALm1gn2Wa8NxFEPPXC4RHqf7BJN4paf3nJRCYQNrWuLlHR3KTYvXdvgyBS/Re/p9To1raoCGQ3fqjzlBCbhdCmwRjDkfLYCJGgd6V6M+1sRXW+XLIPaxIic3XiK9YX1+n51kEJVGF1mvKzpbIS06hkBIIBHiCXAlvmhvV3vGrJyRqyvcflNJCUGMsCy+Ms22petAOD5JUWqMbbPyxZ2Hw4lucxQF2Zku/2dQOGygS18xrFil0cqqgWHwpxL8xYT5XpexQvue2JATjzOXBRFvyBbXREXS70ogH/g1zY+FpI4AjNPbAHNuXo5WkrhE/Mh3vcaXz1XL5aZ9bKxtAQNyMTTszZPeul7ILD5Uhs1ZBuE+7nSQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 08/09/26 3:03 am, Barry Song wrote: > On Mon, Sep 7, 2026 at 1:38 PM Dev Jain wrote: >> >> >> >> On 05/09/26 4:12 pm, Barry Song wrote: >>> On Tue, Sep 1, 2026 at 1:44 PM Dev Jain wrote: >>>> >>>> In preparation for adding a helper to set softleaf ptes in one go, >>>> generalize the swap entry helpers shifting the swap offset by delta, >>>> for softleaves. >>>> >>>> Note that the soft-dirty bit, exclusive bit and uffd bit preservation >>>> will still work for non-swap softleaves, since a softleaf entry is >>>> constructed out of a type and offset, and those bits are ahead of >>>> the soft-dirty, exclusive and uffd bits. >>>> >>>> For example, for a migration entry, pte_swp_exclusive() will return >>>> false, as the exclusivity is encoded in the type itself >>>> (SOFTLEAF_MIGRATION_READ_EXCLUSIVE). >>> >>> I don't quite understand why you mention this. Is anyone calling >>> `pte_swp_exclusive()` on a migration entry? Shouldn't it only be called >>> when `softleaf_is_swap()` is true? >> >> You are right. I just wanted to emphasize the second paragraph - that the >> pte_move_swp_offset will also work for softleaf entries. But I think >> the third para confuses more, I'll drop it. > > I would rather interpret this as meaning that > `pte_move_softleaf_offset` will also work for swap softleafs, > since `pte_move_softleaf_offset` will call some pure-swap > functions？ Yes, so if you see remove_migration_pte, there pte_swp_uffd and pte_swp_soft_dirty are being used. Same with restore_exclusive_pte (for device-exclusive stuff). Which means that pte_swp_exclusive is the only one being used *only* for swap entries. > > Would it be possible to use `if (softleaf_is_swap())` for > these cases to make the intent clearer? or we can > keep both pte_move_softleaf_offset and pte_move_swap_offset? So in my patch I can do if (softleaf_is_swap(entry) && pte_swp_exclusive(pte)) That would make the intent clear. > > As `pte_move_softleaf_offset()` is getting a bit weird now, > a generic softleaf function has a lot of swap-specific code in it: > > static inline pte_t pte_move_softleaf_offset(pte_t pte, long delta) > { > const softleaf_t entry = softleaf_from_pte(pte); > pte_t new = __swp_entry_to_pte(__swp_entry(swp_type(entry), > (swp_offset(entry) > + delta))); > > if (pte_swp_soft_dirty(pte)) > new = pte_swp_mksoft_dirty(new); > if (pte_swp_exclusive(pte)) > new = pte_swp_mkexclusive(new); > if (pte_swp_uffd(pte)) > new = pte_swp_mkuffd(new); > > return new; > } > > Am I missing something here? > >> >>> >>>> >>>> Signed-off-by: Dev Jain >>> >>> Reviewed-by: Barry Song >> >> Thanks. >> >> >>> >>>> --- >>>> mm/internal.h | 29 +++++++++++++++-------------- >>>> mm/memory.c | 4 ++-- >>>> 2 files changed, 17 insertions(+), 16 deletions(-) >>>> >>> [...] >>>> >>>> /** >>>> @@ -523,7 +524,7 @@ static inline pte_t pte_next_swp_offset(pte_t pte) >>>> */ >>>> static inline int swap_pte_batch(pte_t *start_ptep, int max_nr, pte_t pte) >>>> { >>> >>> We might find a user for this in the future, in which case we might >>> want to rename `swap_pte_batch()` to `swap_softleaf_batch()`? >> >> That is what is being done here: >> https://lore.kernel.org/all/20260813-migrate-rmap-batch-v2-1-3c5424c555c7@amd.com/ >> >> I don't have a strong opinion, I can also generalize this right now. > > I don't know how you and Shivank are collaborating, > since you're both changing the same thing at the same time :-) We are not collaborating really : ) he should have ideally waited for my patchset to go in first since I was doing big changes in rmap.c. > > Hopefully, we can get one of yours into mm-new first, > and the other one can find a way to resolve the conflicts. Yes. > >> >> >>> >>>> - pte_t expected_pte = pte_next_swp_offset(pte); >>>> + pte_t expected_pte = pte_next_softleaf_offset(pte); >>> > > Best Regards > Barry