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t=1665157551; a=rsa-sha256; cv=fail; b=HnSKESaTvK9HVnUbyIKlZ90GGALm4WTetc8kApY3G1bosm+tVssB+HUa7HAIcTceyX67Mb jJYPrRTryS7qSXbJUQBLqBljFnxwX3DFt88kncTNcQmJSuERmyX86uY26SjkldDcj/C9+t 2KY+ONieAlAW6fIkhAKj1jCeiPJgdsQ= Authentication-Results: imf16.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=TpnByegO; spf=pass (imf16.hostedemail.com: domain of ira.weiny@intel.com designates 134.134.136.24 as permitted sender) smtp.mailfrom=ira.weiny@intel.com; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}"); dmarc=pass (policy=none) header.from=intel.com X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: 641kui6rss645q4cuix3ktjpcdoxngng X-Rspamd-Queue-Id: 206C8180010 X-HE-Tag: 1665157550-31251 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: On Thu, Oct 06, 2022 at 01:33:31PM -0700, Andrew Morton wrote: > On Wed, 5 Oct 2022 21:05:55 -0700 ira.weiny@intel.com wrote: > > > kmap_to_page() is used to get the page for a virtual address which may > > be kmap'ed. Unfortunately, kmap_local_page() stores mappings in a > > thread local array separate from kmap(). These mappings were not > > checked by the call. > > > > Check the kmap_local_page() mappings and return the page if found. > > > > Because it is intended to remove kmap_to_page() add a warn on once to > > the kmap checks to flag potential issues early. > > What were the user-visible runtime effects of this? No one actually hit a bug with this because AFAIK only one kmap() call has been converted to kmap_local_page() which then eventually calls kmap_to_page(). https://lore.kernel.org/lkml/YzN+ZYLjK6HI1P1C@ZenIV/ However that has already been fixed by Al in that thread. > > Are we able to identify a Fixes:? I suppose this could be added as a Fixes: to the original patch introducing kmap_local_page()? But one could argue that kmap_to_page() was only intended to support kmap() addresses because it does not work with kmap_atomic() addresses either. I'm proposing this as a stop gap to ensure that work can continue on converting kmap() uses to kmap_local_page() without fear of causing breakage while simultaneously we evaluate and hopefully remove kmap_to_page() as well. Ira