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Howlett" , Dave Hansen , Greg Kroah-Hartman , Guenter Roeck , Jann Horn , Jonathan Corbet , Jorge Lucangeli Obes , Matthew Wilcox , Muhammad Usama Anjum , Stephen =?utf-8?Q?R?= =?utf-8?Q?=C3=B6ttger?= , Suren Baghdasaryan , Amer Al Shanawany , Javier Carrasco , Shuah Khan , linux-api@vger.kernel.org, linux-mm@kvack.org, ying.huang@intel.com, feng.tang@intel.com, fengwei.yin@intel.com Subject: Re: [linus:master] [mseal] 8be7258aad: stress-ng.pagemove.page_remaps_per_sec -4.4% regression In-Reply-To: References: <202408041602.caa0372-oliver.sang@intel.com> Date: Tue, 06 Aug 2024 12:14:49 +1000 Message-ID: <87o766iehy.fsf@mail.lhotse> MIME-Version: 1.0 Content-Type: text/plain X-Stat-Signature: zpe54comdwhtex3zu4caigfg7p1zebtq X-Rspamd-Queue-Id: 000FC1A0022 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1722910493-996045 X-HE-Meta: U2FsdGVkX18X6LVIkTsNitE7BTU/prO2RcEeKVPabr/0E/PPGRNIe6GrpM0ZufIWMgsJyUiM+uax45JM3pmw5kXTBIVPy+W7Ys00LcLt3YbclWdbKKD7x7kGsny15fuPEvjFrEbMdhzSiVTvcRfF3fkcuXrVl5FryTST/oMv52ELxgy/WKwgGGn2s/xzAjH7weOfmmhGtb41lwmKFYOwAMNC9BudkLrS3eNfm2N7POfa+F/8K5iXCCQws4TQv6nRnPa9Q17n7AHFKaZ5cdBfBOl7COMcABlNwWPzwe2DGNH1qhdKYm3tn/1rzIMQ1PBnudKuBReqAF7wNHJs5PycMGdzmpJZwo8LB8minxqaOwOtc2GTluvmSGpqJdbPENFGG46AHgJGuCrwfPRO/Ey2oCcwzKGt1iXb9CjMMGcsANs+0/FDOfOuJdZk/YSn8mgtGnsIwOt+L02pk5fQbQEo2rADLX1WvhKs307xhwt6z5igeRVYUq+s2VrXBjVrswsPDWFh/eZy6KVSr2NAuEfL+jPraoIKMcO0ar5pppFgWTlXoj9yE94pPDeFJ9+vA/e0+z/0CuvvldEeTHeZZrS7m3XHMxnxawPAim9WcwNZSDVK+xLR1GhgLzpidAXqjZEZgVPxmFF+JwEFk3kza2HnWCKZF+gKq2D1vQmXk1Sm88jZENEwK82Tl6wUmYKyO333theEhctNFN49g9BJU8MpFuHMRY3ecdaudMJe4aYWBs7/SEA8cXK2GStoaZ0bjQslDyC2bC612LZYoBxqS/JKMr+QDa1iraIV5KizgZrA1NSxPqPdvLNi1TLN30bB2hgIbm+7BE7EYbKzSweB9upGfeS/m2hF1Dn6Vv04EDEnJ0F2Ewm8MC8J79yH+rNL369WcGpxSX601EdRmLQkvXuheJbMvdMfvRfjTkfmvqpdBzz6xGFQLcaBqTASKmHKvfxcR0RWAkt1xVS+RiAGR2g kcdMAYkz AttkWzCwIRSHBCnBmmulLrcmfEUe1E/at9zcKzf5/IqUDcg7xhy3fvJb+zXglOrKCuYhoZLoQCm3osRK5TTHa/6wlqVYLlBfJNBrZgP2KnkDgLur4LpW7B8GNCD4ohes3VpjUGZ9SReGVyt4o0yAaEKg+UPEyVPUfa3t5+HcPR0KSeR3noPOlPJsW0shKiN32PvxQAzNFBPXFsqf4Dct1rpou9bmXfwcnwN+hbSeriUkSzfg++XHHb3/Z+0SAV4dcqIfKu08OZRvtGA8wv8PVMnsYguYMhkOiKi3j4VSzmTINr51cBqD3sUwZltCesO17r8gvzTANRZewupBMVb2JAN/w9w== 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: List-Subscribe: List-Unsubscribe: Linus Torvalds writes: > On Mon, 5 Aug 2024 at 11:55, Linus Torvalds > wrote: >> >> So please consider this a "maybe something like this" patch, but that >> 'arch_unmap()' really is pretty nasty > > Actually, the whole powerpc vdso code confused me. It's not the vvar > thing that wants this close thing, it's the other ones that have the > remap thing. > > .. and there were two of those error cases that needed to reset the > vdso pointer. > > That all shows just how carefully I was reading this code. > > New version - still untested, but now I've read through it one more > time - attached. Needs a slight tweak to compile, vvar_close() needs to return void. And should probably be renamed vdso_close(). Diff below if anyone else wants to test it. I'm testing it now, but it should do what we need. cheers diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c index 6fa041a6690a..431b46976db8 100644 --- a/arch/powerpc/kernel/vdso.c +++ b/arch/powerpc/kernel/vdso.c @@ -81,8 +81,8 @@ static int vdso64_mremap(const struct vm_special_mapping *sm, struct vm_area_str return vdso_mremap(sm, new_vma, &vdso64_end - &vdso64_start); } -static int vvar_close(const struct vm_special_mapping *sm, - struct vm_area_struct *vma) +static void vdso_close(const struct vm_special_mapping *sm, + struct vm_area_struct *vma) { struct mm_struct *mm = vma->vm_mm; mm->context.vdso = NULL; @@ -99,13 +99,13 @@ static struct vm_special_mapping vvar_spec __ro_after_init = { static struct vm_special_mapping vdso32_spec __ro_after_init = { .name = "[vdso]", .mremap = vdso32_mremap, - .close = vvar_close, + .close = vdso_close, }; static struct vm_special_mapping vdso64_spec __ro_after_init = { .name = "[vdso]", .mremap = vdso64_mremap, - .close = vvar_close, + .close = vdso_close, }; #ifdef CONFIG_TIME_NS