On 3/29/2017 10:44 PM, Laura Abbott wrote: > On 03/29/2017 10:04 AM, Laura Abbott wrote: >> On 03/24/2017 05:24 AM, Vinayak Menon wrote: >>> On SPARSEMEM systems page poisoning is enabled after buddy is up, because >>> of the dependency on page extension init. This causes the pages released >>> by free_all_bootmem not to be poisoned. This either delays or misses >>> the identification of some issues because the pages have to undergo another >>> cycle of alloc-free-alloc for any corruption to be detected. >>> Enable page poisoning early by getting rid of the PAGE_EXT_DEBUG_POISON >>> flag. Since all the free pages will now be poisoned, the flag need not be >>> verified before checking the poison during an alloc. >>> >>> Signed-off-by: Vinayak Menon <vinmenon@xxxxxxxxxxxxxx> >>> --- >>> >>> An RFC was sent earlier (http://www.spinics.net/lists/linux-mm/msg123142.html) >>> Not sure if there exists a code path that can free pages to buddy skipping >>> kernel_poison_pages, making the flag PAGE_EXT_DEBUG_POISON a necessity. But >>> the tests have not shown any issues. As per Laura's suggestion, the patch was >>> tested with HIBERNATION enabled and no issues were seen. >>> >> I gave this a spin on some of my machines and it appears to be working >> okay. Thanks Laura. >> I wish we had a bit more context about why it was necessary to track >> the poison in the page itself. >> >> This change means that we shouldn't need the "select PAGE_EXTENSION" >> anymore so that can be dropped. If you do that, you can add >> >> Acked-by: Laura Abbott <labbott@xxxxxxxxxx> >> > Actually never mind on dropping the select. It's still needed for > the guard page as well. Longer term it might be worth separating > that out as well. Realized that there is now some redundant CONFIG_PAGE_POISONING checks in page_ext.c. So along with that I have removed the "select PAGE_EXTENSION"from CONFIG_PAGE_POISONING. Could you please take a look at v2 ? > > You can still take my Ack. > > Thanks, > Laura -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
