The patch titled block: fix memory hotplug and bouncing in block layer has been added to the -mm tree. Its filename is block-fix-memory-hotplug-and-bouncing-in-block-layer.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: block: fix memory hotplug and bouncing in block layer From: Andi Kleen <andi@xxxxxxxxxxxxxx> Only noticed this while hacking something else, no test case. blk_max_low_pfn is initialized once at bootup by the block layer from max_low_pfn. But max_low_pfn is not necessarily constant over the runtime of the system when you consider memory hotplug. What could happen if that someone adds memory later the block layer wouldn't get updated and then start bouncing memory unnecessarily. Also on 64bit blk_max_low_pfn actually isn't needed because it just disables bouncing essentially and there is no highmem. And nobody can pass pfns > max_low_pfn to the block layer, because those wouldn't have a struct page and I suspect block layer wouldn't be very happy without that. So set BLK_BOUNCE_HIGH to infinity (-1ULL) on 64bit. That avoids the problem of having to update it on memory hotadd. On 32bit I kept the same behaviour because at least on i386 memory hotadd only adds HIGHMEM, never lowmem. BLK_BOUNCE_ANY is always set to infinity on both 32 and 64bit. Signed-off-by: Andi Kleen <ak@xxxxxxx> Cc: Jens Axboe <jens.axboe@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/blkdev.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff -puN include/linux/blkdev.h~block-fix-memory-hotplug-and-bouncing-in-block-layer include/linux/blkdev.h --- a/include/linux/blkdev.h~block-fix-memory-hotplug-and-bouncing-in-block-layer +++ a/include/linux/blkdev.h @@ -533,8 +533,13 @@ extern unsigned long blk_max_low_pfn, bl * BLK_BOUNCE_ANY : don't bounce anything * BLK_BOUNCE_ISA : bounce pages above ISA DMA boundary */ + +#if BITS_PER_LONG == 32 #define BLK_BOUNCE_HIGH ((u64)blk_max_low_pfn << PAGE_SHIFT) -#define BLK_BOUNCE_ANY ((u64)blk_max_pfn << PAGE_SHIFT) +#else +#define BLK_BOUNCE_HIGH -1ULL +#endif +#define BLK_BOUNCE_ANY (-1ULL) #define BLK_BOUNCE_ISA (ISA_DMA_THRESHOLD) /* _ Patches currently in -mm which might be from andi@xxxxxxxxxxxxxx are git-x86.patch git-scsi-misc.patch block-fix-memory-hotplug-and-bouncing-in-block-layer.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html