kernel/linux.git/drivers/char/mem.c, branch linux-2.6.16.y

read_zero_pagealigned() locking fix

2007-01-23T15:46:22+00:00

Ramiro Voicu hits the BUG_ON(!pte_none(*pte)) in zeromap_pte_range: kernel bugzilla 7645. Right: read_zero_pagealigned uses down_read of mmap_sem, but another thread's racing read of /dev/zero, or a normal fault, can easily set that pte again, in between zap_page_range and zeromap_page_range getting there. It's been wrong ever since 2.4.3. The simple fix is to use down_write instead, but that would serialize reads of /dev/zero more than at present: perhaps some app would be badly affected. So instead let zeromap_page_range return the error instead of BUG_ON, and read_zero_pagealigned break to the slower clear_user loop in that case - there's no need to optimize for it. Use -EEXIST for when a pte is found: BUG_ON in mmap_zero (the other user of zeromap_page_range), though it really isn't interesting there. And since mmap_zero wants -EAGAIN for out-of-memory, the zeromaps better return that than -ENOMEM. Signed-off-by: Hugh Dickins Signed-off-by: Adrian Bunk

[PATCH] powerpc: iSeries fixes for build with no PCI

2006-01-12T09:09:30+00:00

This reverts part of "ppc64 iSeries: allow build with no PCI" (145d01e4287b8cbf50f87c3283e33bf5c84e8468) which affected generic code and applies a fix in the arch specific code. Commit "partly merge iseries do_IRQ" (5fee9b3b39eb55c7e3619a3b36ceeabffeb8f144) introduced iSeries_get_irq which was only available if CONFIG_PCI is set. Signed-off-by: Stephen Rothwell Signed-off-by: Paul Mackerras

[PATCH] mutex subsystem, semaphore to mutex: VFS, ->i_sem

2006-01-09T23:59:24+00:00

This patch converts the inode semaphore to a mutex. I have tested it on XFS and compiled as much as one can consider on an ia64. Anyway your luck with it might be different. Modified-by: Ingo Molnar (finished the conversion) Signed-off-by: Jes Sorensen Signed-off-by: Ingo Molnar

[PATCH] /dev/mem: validate mmap requests

2006-01-09T04:14:02+00:00

Add a hook so architectures can validate /dev/mem mmap requests. This is analogous to validation we already perform in the read/write paths. The identity mapping scheme used on ia64 requires that each 16MB or 64MB granule be accessed with exactly one attribute (write-back or uncacheable). This avoids "attribute aliasing", which can cause a machine check. Sample problem scenario: - Machine supports VGA, so it has uncacheable (UC) MMIO at 640K-768K - efi_memmap_init() discards any write-back (WB) memory in the first granule - Application (e.g., "hwinfo") mmaps /dev/mem, offset 0 - hwinfo receives UC mapping (the default, since memmap says "no WB here") - Machine check abort (on chipsets that don't support UC access to WB memory, e.g., sx1000) In the scenario above, the only choices are - Use WB for hwinfo mmap. Can't do this because it causes attribute aliasing with the UC mapping for the VGA MMIO space. - Use UC for hwinfo mmap. Can't do this because the chipset may not support UC for that region. - Disallow the hwinfo mmap with -EINVAL. That's what this patch does. Signed-off-by: Bjorn Helgaas Cc: Hugh Dickins Cc: "Luck, Tony" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] /dev/mem __HAVE_PHYS_MEM_ACCESS_PROT tidy-up

2006-01-09T04:14:02+00:00

Tidy up __HAVE_PHYS_MEM_ACCESS_PROT usage to make mmap_mem() easier to read. Signed-off-by: Bjorn Helgaas Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] kmsg_write: don't return printk return value

2006-01-09T04:13:53+00:00

kmsg_write returns with printk, so some programs may be confused by a successful write() with a return value different than the buffer length. # /bin/echo something > /dev/kmsg /bin/echo: write error: Inappropriate ioctl for device The drawbacks is that the printk return value can no more be quickly checked from userspace. Signed-off-by: Guillaume Chazarain Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: re-architect the VM_UNPAGED logic

2005-11-28T22:34:23+00:00

This replaces the (in my opinion horrible) VM_UNMAPPED logic with very explicit support for a "remapped page range" aka VM_PFNMAP. It allows a VM area to contain an arbitrary range of page table entries that the VM never touches, and never considers to be normal pages. Any user of "remap_pfn_range()" automatically gets this new functionality, and doesn't even have to mark the pages reserved or indeed mark them any other way. It just works. As a side effect, doing mmap() on /dev/mem works for arbitrary ranges. Sparc update from David in the next commit. Signed-off-by: Linus Torvalds

[PATCH] unpaged: ZERO_PAGE in VM_UNPAGED

2005-11-22T17:13:42+00:00

It's strange enough to be looking out for anonymous pages in VM_UNPAGED areas, let's not insert the ZERO_PAGE there - though whether it would matter will depend on what we decide about ZERO_PAGE refcounting. But whereas do_anonymous_page may (exceptionally) be called on a VM_UNPAGED area, do_no_page should never be: just BUG_ON. Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge ../linux-2.6 by hand

2005-10-31T02:37:12+00:00

[PATCH] ppc: make phys_mem_access_prot() work with pfns instead of addresses

2005-10-29T04:25:49+00:00

Change the phys_mem_access_prot() function to take a pfn instead of an address. This allows mmap64() to work on /dev/mem for addresses above 4G on 32-bit architectures. We start with a pfn in mmap_mem(), so there's no need to convert to an address; in fact, it's actively bad, since the conversion can overflow when the address is above 4G. Similarly fix the ppc32 page_is_ram() function to avoid a conversion to an address by directly comparing to max_pfn. Working with max_pfn instead of high_memory fixes page_is_ram() to give the right answer for highmem pages. Signed-off-by: Roland Dreier Cc: Anton Blanchard Cc: Benjamin Herrenschmidt Signed-off-by: Andrew Morton Signed-off-by: Paul Mackerras