Hi Andrew, Looks good for NTFS thanks! The only thing is that I think we already have a variable "unsigned long flags" in the function ntfs_end_buffer_async_read() so that could be used instead of redefining it more locally in the if statements. Could you send the patch to Linus? Feel free to add my Acked-by or Signed-off-by "Anton Altaparmakov <aia21@xxxxxxxxxx> line if you wish (I am not bothered either way)... Thanks a lot for fixing it! Best regards, Anton On Tue, 30 Jan 2007, Andrew Morton wrote: > On Mon, 29 Jan 2007 23:27:27 -0800 > Andrew Morton <akpm@xxxxxxxx> wrote: > > > On Sun, 28 Jan 2007 11:25:42 +0100 > > Jiri Slaby <jirislaby@xxxxxxxxx> wrote: > > > > > Andrew Morton napsal(a): > > > > Temporarily at > > > > > > > > http://userweb.kernel.org/~akpm/2.6.20-rc6-mm1/ > > > > > > I'm still seeing this during bootup: > > > BUG: at /home/l/latest/xxx/arch/i386/mm/highmem.c:52 kmap_atomic() > > > [<c0104ffb>] show_trace_log_lvl+0x1a/0x30 > > > [<c01056b5>] show_trace+0x12/0x14 > > > [<c010573c>] dump_stack+0x16/0x18 > > > [<c011b24f>] kmap_atomic+0x16c/0x20e > > > [<c01b279e>] ntfs_end_buffer_async_read+0x18e/0x2ed > > > [<c0183352>] end_bio_bh_io_sync+0x26/0x3f > > > [<c0184dd4>] bio_endio+0x37/0x62 > > > [<c01cda43>] __end_that_request_first+0x224/0x444 > > > [<c01cdc6b>] end_that_request_chunk+0x8/0xa > > > [<c024507d>] scsi_end_request+0x1f/0xc7 > > > [<c02451e6>] scsi_io_completion+0x7b/0x33a > > > [<c024aa5d>] sd_rw_intr+0x23/0x1ab > > > [<c02415ed>] scsi_finish_command+0x42/0x47 > > > [<c0245a38>] scsi_softirq_done+0x64/0xcf > > > [<c01cf9e6>] blk_done_softirq+0x54/0x62 > > > [<c0127bc5>] __do_softirq+0x75/0xde > > > [<c0127c69>] do_softirq+0x3b/0x3d > > > [<c0127ee6>] irq_exit+0x3b/0x3d > > > [<c0106804>] do_IRQ+0x51/0x8d > > > [<c0104a5f>] common_interrupt+0x23/0x28 > > > [<c010241a>] cpu_idle+0x80/0xc3 > > > [<c010140d>] rest_init+0x23/0x36 > > > [<c045ea59>] start_kernel+0x3a5/0x43c > > > [<00000000>] 0x0 > > > ======================= > > > > > > I.e. KM_BIO_SRC_IRQ through softirq path. > > > > > > > argh. > > > > ntfs_end_buffer_async_read() doesn't know whether it will be called from > > hardirq or from softirq context: it depends upon the underlying driver. > > > > In this case, if the CPU running ntfs_end_buffer_async_read() is > > interrupted by IO completion against a different disk controller and that > > completion handler uses KM_BIO_SRC_IRQ (as it is allowed to do), it will > > trash ntfs_end_buffer_async_read()'s atomic kmap and unpleasing things will > > ensue. > > > > I guess a suitable fix here is to protect that kmap with > > local_irq_save/restore. > > > > I wonder where else we have that bug? > > Actually, this isn't related to softirq-vs-hardirq. Most interrupt > handlers are interruptible, so the rule is simply that KM_BIO_SRC_IRQ must > always be taken under local_irq_disable(). > > A quick scan indicates that the following files might be buggy in this > regard: > > drivers/mmc/wbsd.c > drivers/mmc/at91_mci.c > drivers/mmc/sdhci.c > drivers/scsi/scsi_lib.c when called from stex.c > fs/ntfs/aops.c > > Happily, KM_BIO_DST_IRQ has no users and can presumably be removed. > > > Fixes for stex and ntfs follow. > > > From: Andrew Morton <akpm@xxxxxxxx> > > The KM_BIO_SRC_IRQ kmap slot requires local irq protection. > > Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxx> > Cc: Ed Lin <ed.lin@xxxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxx> > --- > > drivers/scsi/stex.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff -puN drivers/scsi/stex.c~stex-kmap_atomic-atomicity-fix drivers/scsi/stex.c > --- a/drivers/scsi/stex.c~stex-kmap_atomic-atomicity-fix > +++ a/drivers/scsi/stex.c > @@ -459,15 +459,19 @@ static void stex_internal_copy(struct sc > *count = cmd->request_bufflen; > lcount = *count; > while (lcount) { > + unsigned long flags = flags; /* Suppress uninit warning */ > + > len = lcount; > s = (void *)src; > if (cmd->use_sg) { > size_t offset = *count - lcount; > s += offset; > + local_irq_save(flags); > base = scsi_kmap_atomic_sg(cmd->request_buffer, > sg_count, &offset, &len); > if (base == NULL) { > *count -= lcount; > + local_irq_restore(flags); > return; > } > d = base + offset; > @@ -480,8 +484,10 @@ static void stex_internal_copy(struct sc > memcpy(s, d, len); > > lcount -= len; > - if (cmd->use_sg) > + if (cmd->use_sg) { > scsi_kunmap_atomic_sg(base); > + local_irq_restore(flags); > + } > } > } > > _ > > > > From: Andrew Morton <akpm@xxxxxxxx> > > The KM_BIO_SRC_IRQ kmap slot requires local irq protection. > > Cc: Anton Altaparmakov <aia21@xxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxx> > --- > > fs/ntfs/aops.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff -puN fs/ntfs/aops.c~ntfs-kmap_atomic-atomicity-fix fs/ntfs/aops.c > --- a/fs/ntfs/aops.c~ntfs-kmap_atomic-atomicity-fix > +++ a/fs/ntfs/aops.c > @@ -88,14 +88,17 @@ static void ntfs_end_buffer_async_read(s > if (unlikely(file_ofs + bh->b_size > init_size)) { > u8 *kaddr; > int ofs; > + unsigned long flags; > > ofs = 0; > if (file_ofs < init_size) > ofs = init_size - file_ofs; > + local_irq_save(flags); > kaddr = kmap_atomic(page, KM_BIO_SRC_IRQ); > memset(kaddr + bh_offset(bh) + ofs, 0, > bh->b_size - ofs); > kunmap_atomic(kaddr, KM_BIO_SRC_IRQ); > + local_irq_restore(flags); > flush_dcache_page(page); > } > } else { > @@ -138,16 +141,19 @@ static void ntfs_end_buffer_async_read(s > u8 *kaddr; > unsigned int i, recs; > u32 rec_size; > + unsigned long flags; > > rec_size = ni->itype.index.block_size; > recs = PAGE_CACHE_SIZE / rec_size; > /* Should have been verified before we got here... */ > BUG_ON(!recs); > + local_irq_save(flags); > kaddr = kmap_atomic(page, KM_BIO_SRC_IRQ); > for (i = 0; i < recs; i++) > post_read_mst_fixup((NTFS_RECORD*)(kaddr + > i * rec_size), rec_size); > kunmap_atomic(kaddr, KM_BIO_SRC_IRQ); > + local_irq_restore(flags); > flush_dcache_page(page); > if (likely(page_uptodate && !PageError(page))) > SetPageUptodate(page); > _ > > Best regards, Anton -- Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @) Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK Linux NTFS maintainer, http://www.linux-ntfs.org/ - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
