From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 6 Jul 2001 15:41:38 +0200 From: Andrea Arcangeli Subject: Re: patch: highmem zero-bounce Message-ID: <20010706154138.O2425@athlon.random> References: <20010626182215.C14460@suse.de> <20010627114155.A31910@athlon.random> <20010627182745.D17905@suse.de> <20010627184908.E17905@suse.de> <20010627190626.E24623@athlon.random> <20010627191229.G17905@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20010627191229.G17905@suse.de>; from axboe@suse.de on Wed, Jun 27, 2001 at 07:12:29PM +0200 Sender: owner-linux-mm@kvack.org Return-Path: To: Jens Axboe Cc: Linux Kernel , linux-mm@kvack.org, "ZINKEVICIUS,MATT (HP-Loveland,ex1)" List-ID: On Wed, Jun 27, 2001 at 07:12:29PM +0200, Jens Axboe wrote: > Humm yes, I agree. I'll redo it tonight and send an updated > incremental. Hopefully I'll be able to upload a new full version too. I was going to integrate the avoid-bounce-buffer support but I don't find anything recent except the bio patch for 2.5 that you uploaded yesterday: andrea@athlon:~/mirror/kernel.org/people/axboe > find -mtime -1 ./v2.5 ./v2.5/bio-14-pre4 andrea@athlon:~/mirror/kernel.org/people/axboe > find -mtime -25 ./v2.5 ./v2.5/bio-14-pre4 andrea@athlon:~/mirror/kernel.org/people/axboe > The bio patch would better be 2.5 material, I'd prefer only skipping the bounce between 1G to 4G in 2.4. Could you make a new patch with only the bounce skip between 1G and 4G against pre3? btw, the latest bio patch from yesterday is still broken with respect to nested irqs: +static inline void *kmap_atomic(struct page *page, enum km_type type) +{ + unsigned long flags; + void *vaddr; + + __save_flags(flags); + __cli(); + vaddr = __kmap_atomic(page, type); + __restore_flags(flags); + + return vaddr; +} [..] +static inline void kunmap_atomic(void *kvaddr, enum km_type type) +{ +#if HIGHMEM_DEBUG + unsigned long flags; + + __save_flags(flags); + __cli(); + __kunmap_atomic(kvaddr, type); + __restore_flags(flags); #endif } [..] +#define bio_kmap_irq(bio) (kmap_atomic(bio_page((bio)), KM_BIO_IRQ) + bio_offset((bio))) +#define bio_kunmap_irq(ptr) kunmap_atomic((void *) (((unsigned long) (ptr)) & PAGE_MASK), KM_BIO_IRQ) [..] +extern inline void *ide_map_buffer(struct request *rq) +{ + return bio_kmap_irq(rq->bio) + ide_rq_offset(rq); +} + +extern inline void ide_unmap_buffer(char *buffer) +{ + bio_kunmap_irq(buffer); +} [..] + char *to = ide_map_buffer(rq); + idedisk_output_data (drive, to, SECTOR_WORDS); + ide_unmap_buffer(to); [..] the __cli() and __restore_flags() are not needed in kmap_atomic, and the bio_kmap_irq is still broken, the suprious __restore_flags in kmap_atomic is enabling irq again before you do the PIO, that will corrupt the pte of the KM_BIO_IRQ if a nested irq runs under us. In short you don't need to __save_flags(); __cli() for all the KM but the BIO_IRQ one, and in the BIO_IRQ case you need to __restore_flags not after setting the pagetable, but after also all the I/O is finished (so in the kunmap, not in the kmap). Andrea -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/