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[209.85.208.45]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b7654fd4e6bsm291444266b.34.2025.11.20.13.37.53 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 20 Nov 2025 13:37:53 -0800 (PST) Received: by mail-ed1-f45.google.com with SMTP id 4fb4d7f45d1cf-640860f97b5so2058547a12.2 for ; Thu, 20 Nov 2025 13:37:53 -0800 (PST) X-Forwarded-Encrypted: i=1; AJvYcCUbkWV/qkoGE3fBtDc6Ar/oMFw23DyCGoKXAPoQ5WAjCsmx1JQb9stQ6CrGauD0RpBh0MVxIhaNxQ==@kvack.org X-Received: by 2002:a05:6402:90c:b0:63b:f67b:3782 with SMTP id 4fb4d7f45d1cf-64554692891mr155989a12.27.1763674673251; Thu, 20 Nov 2025 13:37:53 -0800 (PST) MIME-Version: 1.0 References: <3f4ec3be-0725-43cc-a75b-72549ebdc5c9@suse.cz> In-Reply-To: From: Linus Torvalds Date: Thu, 20 Nov 2025 13:37:36 -0800 X-Gmail-Original-Message-ID: X-Gm-Features: AWmQ_bke52G7Xf5XSH-fAxcjB8H4OhPHmCg2i731CLXDdQlXY8OHLgDLjc_6dog Message-ID: Subject: Re: [GIT PULL] slab fix for 6.18-rc7 To: Matthew Wilcox Cc: Vlastimil Babka , Andrew Morton , Harry Yoo , David Rientjes , Christoph Lameter , Roman Gushchin , "linux-mm@kvack.org" , LKML , Christoph Hellwig Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 39B3014000F X-Rspamd-Server: rspam07 X-Stat-Signature: xfokbzmmrm9xwy86sk5je6a3eiyrc8oq X-Rspam-User: X-HE-Tag: 1763674676-22793 X-HE-Meta: U2FsdGVkX18j66/Bdgr452vLBHNstsEjpIkO87zhipz0MPj8ku11AsyYSx+HWpamLBvyxpVUrrxcEcMdiduAo9PExXgKZUjk86pxKLYz0uxMJxTF23cI4Rza3hVdcHwUUDIgEh3uqAInuv6jT+LvGcL6OoOJFoFrlSjtGAeBJnysDsDircSbdd/D1ZkEEQWlGwqrPY86tqxqyB/2CL45pNPpxWzn6xyaNOcZCPlv9N5Y6rZSIL/gdCSJBEiaJtvRevyrkPqs8Q/B9JdZ+DtEq2C/a0tOGKVLx5630M2A9LNHR20QeOi25u/pNXwjRtFKaqQr1ec3M3LzJ5PN6iRN+LkWIigBKhgesmKKFAbUnoBUEAqQKaPb3uZx1qnxGZUmNSj78zl4lbcamX59aU7JflkM3YrJDdCLbhSL9itfbFIxaetsY8qCx49oGo57qJRZzJp5pfMGwIQ1JSLI4y4dmzf/LTPXoixPull2zbPWJswhF81+eZzCBGjdlo70EHSrQygbVbgjCdwQa4KpPAS27YPJgxvS5rEWaFZw5b/ZOui0NlIhgyFPw7wgPfCtnMlNDhQU8H7Vql4a4z4m47KSpwN5YFjpptd2U1Fq7jZjc1/6hUZ9lyCu6UWS1nCvEEuYphovmvSyyG3VhQSB2lYML9Yh10dZMsxm7j/HPHHpXA1kgSw+PwOvH09MlSdjmz4pcMOyyK7xnWhgaiPsAPfU4EKRbGPv6aYuewEVHYVr4mPp0qowsY8M0x/phgSsZeUknQW4jQkwKXcwDotoAS4HEL0j5AHWeMx7Y16Ac6mUjiatmD5nznr9HERRWYPGPmIpDMDPUvOBmS02ZKvJ/7RaWtXUvJfHl5nZZt1AJo1FDdjJiHqIdsm6vDjIpx/KlbbJh1LqGvEMfEj+/Riwe30AyvbHIfISdUuiFDz7zZz5tTCMtULnRjxfBYUL7y4HI8ozhxcAZXhuca8/m61JQM3 oPW1ukdR 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 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: On Thu, 20 Nov 2025 at 12:11, Matthew Wilcox wrote: > > Would you rather see something like this that hides the fact it's > dealing with HIGHMEM? NO! I would rather see us stop writing WORSE CODE due to the abomination that is HIGHMEM. > @@ -67,11 +67,19 @@ static void check_element(mempool_t *pool, void *element) You just added more lines of code to deal with something that we shouldn't spend one second of time on, and that we should *not* write more complex code for. IOW, I think what should happen is just something like below. IOW, just remove the useless garbage. Think of it as a small step towards the eventual bright future that is lack of HIGHMEM. HIGHMEM was a mistake forced on us by bad hardware. We should revel in the fact that it is not really relevant any more. Linus --- diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index 32b65073d0cc..ecfb65c09651 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -58,7 +58,7 @@ config SLUB_DEBUG config SLUB_DEBUG_ON bool "SLUB debugging on by default" - depends on SLUB_DEBUG + depends on SLUB_DEBUG && !HIGHMEM select STACKDEPOT_ALWAYS_INIT if STACKTRACE_SUPPORT default n help diff --git a/mm/mempool.c b/mm/mempool.c index d7bbf1189db9..22157d23cdd9 100644 --- a/mm/mempool.c +++ b/mm/mempool.c @@ -12,7 +12,6 @@ #include #include -#include #include #include #include @@ -68,20 +67,9 @@ static void check_element(mempool_t *pool, void *element) } else if (pool->free == mempool_free_pages) { /* Mempools backed by page allocator */ int order = (int)(long)pool->pool_data; - -#ifdef CONFIG_HIGHMEM - for (int i = 0; i < (1 << order); i++) { - struct page *page = (struct page *)element; - void *addr = kmap_local_page(page + i); - - __check_element(pool, addr, PAGE_SIZE); - kunmap_local(addr); - } -#else void *addr = page_address((struct page *)element); __check_element(pool, addr, PAGE_SIZE << order); -#endif } } @@ -107,20 +95,9 @@ static void poison_element(mempool_t *pool, void *element) } else if (pool->alloc == mempool_alloc_pages) { /* Mempools backed by page allocator */ int order = (int)(long)pool->pool_data; - -#ifdef CONFIG_HIGHMEM - for (int i = 0; i < (1 << order); i++) { - struct page *page = (struct page *)element; - void *addr = kmap_local_page(page + i); - - __poison_element(addr, PAGE_SIZE); - kunmap_local(addr); - } -#else void *addr = page_address((struct page *)element); __poison_element(addr, PAGE_SIZE << order); -#endif } } #else /* CONFIG_SLUB_DEBUG_ON */