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b=o7y49xd1bIJss61h943uGovO6C ndWFoS+qBoj2F4mMR/4Pax/u0+HLveLzEm5oqc87spBpJbgjwDW1RViTTYttbelqxTST3Sgq0LwY1 0jWs6lyb2EpBQiaPxlApurqaG/JgLTstPzf0HqHXGYzgB8z8fz+lugiiG/OHTJBpkMvXPHNiqu7uD ioRQNeqtWPrI7fp/39IvGYqOZwrLPRFw/gxpYGkY27LgQLE5lnUg/jiqJFeBn+tLJtB5YmAdj7mQ6 IStDtWHQ707sDjH//GCPmWtdektwZ0Yp5+ie+Y4CPQ8zwRIcqU44/vtpiFQXbFpGb3N7HSVIK7ke5 dnhe6i3A==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vMAzl-00000001jnZ-0eR7; Thu, 20 Nov 2025 20:11:09 +0000 Date: Thu, 20 Nov 2025 20:11:08 +0000 From: Matthew Wilcox To: Linus Torvalds Cc: Vlastimil Babka , Andrew Morton , Harry Yoo , David Rientjes , Christoph Lameter , Roman Gushchin , "linux-mm@kvack.org" , LKML , Christoph Hellwig Subject: Re: [GIT PULL] slab fix for 6.18-rc7 Message-ID: References: <3f4ec3be-0725-43cc-a75b-72549ebdc5c9@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 9379E1C0006 X-Stat-Signature: d7zsqf7igk9umz8655ea5aaac8yerdn3 X-HE-Tag: 1763669474-395799 X-HE-Meta: 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 s4uoWBj7 WnnhjoFG6qh5a/+Z84n+zAidJAn8KBNj19pjaH0719qEZNvaLOTAtl18WamtAlO32J7aZBZnQ+NovMJIR4coY5Aw5koBppHJ16fg5WSIw75q2ygkPqTCgsrHzjzpCTEe5eju2zlt8DMHfUIP85Xm8t/lLERr27GVvBVANjovZIbxh+2+GdPTGt3J7HMLaG2VCrlLgVLSyno7FZkguk0sWjQqQgPHngIIEqw7U0eQovjdCB5mm8f050sHMUXRmAI2Gqyh1X0UXkgRPEmNCBGbqDgtHrXTIRD3jGk4Y 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, Nov 20, 2025 at 10:58:13AM -0800, Linus Torvalds wrote: > On Thu, 20 Nov 2025 at 10:45, Vlastimil Babka wrote: > > > > * Fix mempool poisoning order>0 pages with CONFIG_HIGHMEM (Vlastimil Babka) > > I've pulled this, but honestly, CONFIG_HIGHMEM should be considered a > dying breed, and I'd have been happier with just not adding extra code > for that thing. Would you rather see something like this that hides the fact it's dealing with HIGHMEM? diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 0091ad1986bf..68b952e68176 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -623,8 +623,10 @@ PAGEFLAG_FALSE(HighMem, highmem) /* Does kmap_local_folio() only allow access to one page of the folio? */ #ifdef CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP #define folio_test_partial_kmap(f) true +#define PagePartialKmap(p) true #else #define folio_test_partial_kmap(f) folio_test_highmem(f) +#define PagePartialKmap(p) PageHighMem(p) #endif #ifdef CONFIG_SWAP diff --git a/mm/mempool.c b/mm/mempool.c index 1c38e873e546..b1f5d81d70c6 100644 --- a/mm/mempool.c +++ b/mm/mempool.c @@ -67,11 +67,19 @@ static void check_element(mempool_t *pool, void *element) __check_element(pool, element, kmem_cache_size(pool->pool_data)); } else if (pool->free == mempool_free_pages) { /* Mempools backed by page allocator */ - int order = (int)(long)pool->pool_data; - void *addr = kmap_local_page((struct page *)element); - - __check_element(pool, addr, 1UL << (PAGE_SHIFT + order)); - kunmap_local(addr); + size_t len = 1UL << (long)pool->pool_data; + do { + struct page *page = (struct page *)element; + void *addr = kmap_local_page(page); + size_t chunk = len; + + if (PagePartialKmap(page) && chunk > PAGE_SIZE) + chunk = PAGE_SIZE; + __check_element(pool, addr, chunk); + kunmap_local(addr); + len -= chunk; + element += chunk; + } while (len > 0); } } (not actually tested, but based on memcpy_from_folio())