The patch titled mm: vmalloc fix lazy unmapping cache aliasing has been added to the -mm tree. Its filename is mm-vmalloc-fix-lazy-unmapping-cache-aliasing.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://userweb.kernel.org/~akpm/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: mm: vmalloc fix lazy unmapping cache aliasing From: Nick Piggin <npiggin@xxxxxxx> Jim Radford has reported that the vmap subsystem rewrite was sometimes causing his VIVT ARM system to behave strangely (seemed like going into infinite loops trying to fault in pages to userspace). We determined that the problem was most likely due to a cache aliasing issue. flush_cache_vunmap was only being called at the moment the page tables were to be taken down, however with lazy unmapping, this can happen after the page has subsequently been freed and allocated for something else. The dangling alias may still have dirty data attached to it. The fix for this problem is to do the cache flushing when the caller has called vunmap -- it would be a bug for them to write anything else to the mapping at that point. That appeared to solve Jim's problems. Reported-by: Jim Radford <radford@xxxxxxxxxxxxx> Signed-off-by: Nick Piggin <npiggin@xxxxxxx> Cc: Russell King <rmk@xxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/vmalloc.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff -puN mm/vmalloc.c~mm-vmalloc-fix-lazy-unmapping-cache-aliasing mm/vmalloc.c --- a/mm/vmalloc.c~mm-vmalloc-fix-lazy-unmapping-cache-aliasing +++ a/mm/vmalloc.c @@ -77,7 +77,6 @@ static void vunmap_page_range(unsigned l BUG_ON(addr >= end); pgd = pgd_offset_k(addr); - flush_cache_vunmap(addr, end); do { next = pgd_addr_end(addr, end); if (pgd_none_or_clear_bad(pgd)) @@ -543,9 +542,10 @@ static void purge_vmap_area_lazy(void) } /* - * Free and unmap a vmap area + * Free and unmap a vmap area, caller ensuring flush_cache_vunmap had been + * called for the correct range previously. */ -static void free_unmap_vmap_area(struct vmap_area *va) +static void free_unmap_vmap_area_noflush(struct vmap_area *va) { va->flags |= VM_LAZY_FREE; atomic_add((va->va_end - va->va_start) >> PAGE_SHIFT, &vmap_lazy_nr); @@ -553,6 +553,15 @@ static void free_unmap_vmap_area(struct try_purge_vmap_area_lazy(); } +/* + * Free and unmap a vmap area + */ +static void free_unmap_vmap_area(struct vmap_area *va) +{ + flush_cache_vunmap(va->va_start, va->va_end); + free_unmap_vmap_area_noflush(va); +} + static struct vmap_area *find_vmap_area(unsigned long addr) { struct vmap_area *va; @@ -734,7 +743,7 @@ static void free_vmap_block(struct vmap_ spin_unlock(&vmap_block_tree_lock); BUG_ON(tmp != vb); - free_unmap_vmap_area(vb->va); + free_unmap_vmap_area_noflush(vb->va); call_rcu(&vb->rcu_head, rcu_free_vb); } @@ -820,6 +829,8 @@ static void vb_free(const void *addr, un free_vmap_block(vb); } else spin_unlock(&vb->lock); + + flush_cache_vunmap((unsigned long)addr, (unsigned long)addr + size); } /** _ Patches currently in -mm which might be from npiggin@xxxxxxx are mm-vmalloc-allocator-off-by-one.patch mm-vmalloc-failure-flush-fix.patch mm-vmalloc-search-restart-fix.patch mm-vmalloc-fix-lazy-unmapping-cache-aliasing.patch linux-next.patch mm-dont-mark_page_accessed-in-fault-path.patch mm-dont-mark_page_accessed-in-shmem_fault.patch mm-invoke-oom-killer-from-page-fault.patch mm-invoke-oom-killer-from-page-fault-fix.patch mm-invoke-oom-killer-from-page-fault-fix-fix-2.patch mm-write_cache_pages-cyclic-fix.patch mm-write_cache_pages-cyclic-fix-fix.patch mm-write_cache_pages-early-loop-termination.patch mm-write_cache_pages-writepage-error-fix.patch mm-write_cache_pages-integrity-fix.patch mm-write_cache_pages-cleanups.patch mm-write_cache_pages-optimise-page-cleaning.patch mm-write_cache_pages-terminate-quickly.patch mm-write_cache_pages-more-terminate-quickly.patch mm-do_sync_mapping_range-integrity-fix.patch mm-get-rid-of-pagevec_release_nonlru.patch mm-more-likely-reclaim-madv_sequential-mappings.patch mm-vmalloc-tweak-failure-printk.patch mm-vmalloc-improve-vmallocinfo.patch mm-vmalloc-use-mutex-for-purge.patch mm-vmalloc-make-lazy-unmapping-configurable.patch reiser4.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