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([2620:10d:c092:500::4:45e4]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-aec6caef924sm1075303366b.156.2025.07.23.10.07.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Jul 2025 10:07:51 -0700 (PDT) Message-ID: <003c12a7-cb3b-4bbd-86ac-4caaddcabf26@gmail.com> Date: Wed, 23 Jul 2025 18:07:48 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH POC] prctl: extend PR_SET_THP_DISABLE to optionally exclude VM_HUGEPAGE To: David Hildenbrand , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, Jonathan Corbet , Andrew Morton , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , SeongJae Park , Jann Horn , Yafang Shao , Matthew Wilcox References: <20250721090942.274650-1-david@redhat.com> <4a8b70b1-7ba0-4d60-a3a0-04ac896a672d@gmail.com> <5968efc3-50ac-465a-a51b-df91fc1a930a@redhat.com> Content-Language: en-US From: Usama Arif In-Reply-To: <5968efc3-50ac-465a-a51b-df91fc1a930a@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit >> Thanks for the patch David! >> >> As discussed in the other thread, with the below diff >> >> diff --git a/kernel/sys.c b/kernel/sys.c >> index 2a34b2f70890..3912f5b6a02d 100644 >> --- a/kernel/sys.c >> +++ b/kernel/sys.c >> @@ -2447,7 +2447,7 @@ static int prctl_set_thp_disable(unsigned long thp_disable, unsigned long flags, >>                  return -EINVAL; >>            /* Flags are only allowed when disabling. */ >> -       if (!thp_disable || (flags & ~PR_THP_DISABLE_EXCEPT_ADVISED)) >> +       if ((!thp_disable && flags) || (flags & ~PR_THP_DISABLE_EXCEPT_ADVISED)) >>                  return -EINVAL; >>          if (mmap_write_lock_killable(current->mm)) >>                  return -EINTR; >> >> >> I tested with the below selftest, and it works. It hopefully covers >> majority of the cases including fork and re-enabling THPs. >> Let me know if it looks ok and please feel free to add this in the >> next revision you send. >> >> >> Once the above diff is included, please feel free to add >> >> Acked-by: Usama Arif >> Tested-by: Usama Arif > > Thanks! > > The latest version lives at > >   https://github.com/davidhildenbrand/linux/tree/PR_SET_THP_DISABLE > > With all current review feedback addressed (primarily around description+comments) + that one fix. > > Hi David, Just wanted to check if the above branch is up to date? I didn't check the description/comments, but it still has [1]: if (!thp_disable || (flags & ~PR_THP_DISABLE_EXCEPT_ADVISED)) and not if ((!thp_disable && flags) || (flags & ~PR_THP_DISABLE_EXCEPT_ADVISED)) in prctl_set_thp_disable, which is causing the reset to system policy case in my selftest to fail. [1] https://github.com/davidhildenbrand/linux/commit/5711cdf5dfe65ca28dac2a57d62e18f1475dac57#diff-dc9985831020a20a54baf023fec641593d0d4e75a78988c3b35a176aff1c0321R2450 Thanks, Usama