The increased use of pdtlb/pitlb instructions seemed to increase the frequency of random segmentation faults building packages. Further, we had a number of cases where TLB inserts would repeatedly fail and all forward progress would stop. The Haskell ghc package caused a lot of trouble in this area. The final indication of a race in pte handling was this syslog entry on sibaris (C8000): swap_free: Unused swap offset entry 00000004 BUG: Bad page map in process mysqld pte:00000100 pmd:019bbec5 addr:00000000ec464000 vm_flags:00100073 anon_vma:0000000221023828 mapping: (null) index:ec464 CPU: 1 PID: 9176 Comm: mysqld Not tainted 4.0.0-2-parisc64-smp #1 Debian 4.0.5-1 Backtrace: [<0000000040173eb0>] show_stack+0x20/0x38 [<0000000040444424>] dump_stack+0x9c/0x110 [<00000000402a0d38>] print_bad_pte+0x1a8/0x278 [<00000000402a28b8>] unmap_single_vma+0x3d8/0x770 [<00000000402a4090>] zap_page_range+0xf0/0x198 [<00000000402ba2a4>] SyS_madvise+0x404/0x8c0 Note that the pte value is 0 except for the accessed bit 0x100. This bit shouldn't be set without the present bit. It should be noted that the madvise system call is probably a trigger for many of the random segmentation faults. In looking at the kernel code, I found the following problems: 1) The pte_clear define didn't take TLB lock when clearing a pte. 2) We didn't test pte present bit inside lock in exception support. 3) The pte and tlb locks needed to merged in order to ensure consistency between page table and TLB. This also has the effect of serializing TLB broadcasts on SMP systems. The attached change implements the above and a few other tweaks to try to improve performance. Based on the timing code, TLB purges are very slow (e.g., ~ 209 cycles per page on rp3440). Thus, I think it beneficial to test the split_tlb variable to avoid duplicate purges. Probably, all PA 2.0 machines have combined TLBs. I dropped using __flush_tlb_range in flush_tlb_mm as I realized all applications and most threads have a stack size that is too large to make this useful. I added some comments to this effect. Since implementing 1 through 3, I haven't had any random segmentation faults on mx3210 (rp3440) in about one week of building code and running as a Debian buildd. Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: stable@vger.kernel.org # v3.18+ Signed-off-by: Helge Deller <deller@gmx.de>
On parisc, SHMLBA was defined to 0x00400000 (4MB) to reflect that we need to take care of our caches for shared mappings. But actually, we can map a file at any multiple address of PAGE_SIZE, so let us correct that now with a value of PAGE_SIZE for SHMLBA. Instead we now take care of this cache colouring via the constant SHM_COLOUR while we map shared pages. Signed-off-by: Helge Deller <deller@gmx.de> CC: Jeroen Roovers <jer@gentoo.org> CC: John David Anglin <dave.anglin@bell.net> CC: Carlos O'Donell <carlos@systemhalted.org> Cc: stable@kernel.org [3.13+]
The attached change removes the unused and experimental CONFIG_PARISC_TMPALIAS code. It doesn't work and I don't believe it will ever be used. Signed-off-by: John David Anglin <dave.anglin@bell.net> Signed-off-by: Helge Deller <deller@gmx.de>
This commit: f8dae00684d678afa13041ef170cecfd1297ed40: parisc: Ensure full cache coherency for kmap/kunmap caused negative caching side-effects, e.g. hanging processes with expect and too many inequivalent alias messages from flush_dcache_page() on Debian 5 systems. This patch now partly reverts it and has been in production use on our debian buildd makeservers since a week without any major problems. Signed-off-by: Helge Deller <deller@gmx.de> Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: stable@vger.kernel.org # v3.9+ Signed-off-by: Helge Deller <deller@gmx.de>
Helge Deller noted a few weeks ago problems with the AIO support on parisc. This change is the result of numerous iterations on how best to deal with this problem. The solution adopted here is to provide full cache coherency in a uniform manner on all parisc systems. This involves calling flush_dcache_page() on kmap operations and flush_kernel_dcache_page() on kunmap operations. As a result, the copy_user_page() and clear_user_page() functions can be removed and the overall code is simpler. The change ensures that both userspace and kernel aliases to a mapped page are invalidated and flushed. This is necessary for the correct operation of PA8800 and PA8900 based systems which do not support inequivalent aliases. With this change, I have observed no cache related issues on c8000 and rp3440. It is now possible for example to do kernel builds with "-j64" on four way systems. On systems using XFS file systems, the patch recently posted by Mikulas Patocka to "fix crash using XFS on loopback" is needed to avoid a hang caused by an uninitialized lock passed to flush_dcache_page() in the page struct. Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: stable@vger.kernel.org # v3.9+ Signed-off-by: Helge Deller <deller@gmx.de>
This reverts commit 320c90be7ba1c371e882edff57272a89b213d136. Christoph Hellwig <hch@infradead.org> commented: This one shouldn't go in - Geert sent it a bit prematurely, as Lustre shouldn't use it just to reimplement core VM functionality (which it shouldn't use either, but that's a separate story). Signed-off-by: Helge Deller <deller@gmx.de>
ERROR: "flush_cache_page" [drivers/staging/lustre/lustre/libcfs/libcfs.ko] undefined! Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Helge Deller <deller@gmx.de>
The parisc architecture does not have a pte special bit. As a result, special mappings are handled with the VM_PFNMAP and VM_MIXEDMAP flags. VM_MIXEDMAP mappings may or may not have a "struct page" backing. When pfn_valid() is false, there is no "struct page" backing. Otherwise, they are treated as normal pages. The FireGL driver uses the VM_MIXEDMAP without a backing "struct page". This treatment caused a panic due to a TLB data miss in update_mmu_cache. This appeared to be in the code generated for page_address(). We were in fact using a very circular bit of code to determine the physical address of the PFN in various cache routines. This wasn't valid when there was no "struct page" backing. The needed address can in fact be determined simply from the PFN itself without using the "struct page". The attached patch updates update_mmu_cache(), flush_cache_mm(), flush_cache_range() and flush_cache_page() to check pfn_valid() and to directly compute the PFN physical and virtual addresses. Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: <stable@vger.kernel.org> # 3.10 Signed-off-by: Helge Deller <deller@gmx.de>
I still see the occasional random segv on rp3440. Looking at one of these (a code 15), it appeared the problem must be with the cache handling of anonymous pages. Reviewing this, I noticed that the space register %sr1 might be being clobbered when we flush an anonymous page. Register %sr1 is used for TLB purges in a couple of places. These purges are needed on PA8800 and PA8900 processors to ensure cache consistency of flushed cache lines. The solution here is simply to move the %sr1 load into the TLB lock region needed to ensure that one purge executes at a time on SMP systems. This was already the case for one use. After a few days of operation, I haven't had a random segv on my rp3440. Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: <stable@vger.kernel.org> # 3.10 Signed-off-by: Helge Deller <deller@gmx.de>
kmap_atomic allows only one argument now, just move the second. Signed-off-by: Zhao Hongjiang <zhaohongjiang@huawei.com> Signed-off-by: Helge Deller <deller@gmx.de>