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Violators will be prosecuted for from ; Mon, 13 Nov 2017 04:59:24 -0000 From: "Aneesh Kumar K.V" To: Nicholas Piggin , linuxppc-dev@lists.ozlabs.org Cc: Nicholas Piggin , Michael Ellerman , Florian Weimer , "Kirill A. Shutemov" Subject: Re: [PATCH v2 1/5] powerpc/64s/hash: Fix 128TB-512TB virtual address boundary case allocation In-Reply-To: <20171109172740.19681-2-npiggin@gmail.com> References: <20171109172740.19681-1-npiggin@gmail.com> <20171109172740.19681-2-npiggin@gmail.com> Date: Mon, 13 Nov 2017 10:29:19 +0530 MIME-Version: 1.0 Content-Type: text/plain Message-Id: <87h8tysriw.fsf@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Nicholas Piggin writes: > When allocating VA space with a hint that crosses 128TB, the SLB addr_limit > variable is not expanded if addr is not > 128TB, but the slice allocation > looks at task_size, which is 512TB. This results in slice_check_fit() > incorrectly succeeding because the slice_count truncates off bit 128 of the > requested mask, so the comparison to the available mask succeeds. > > Fix this by using mm->context.addr_limit instead of mm->task_size for > testing allocation limits. This causes such allocations to fail. > Also note that this change the rule from > 128TB to >-128TB to select the larger address space. I guess that is correct because without '>=' we won't be able to allocate anything starting from 128TB (except MAP_FIXED). Reviewed-by: Aneesh Kumar K.V > Cc: "Aneesh Kumar K.V" > Fixes: f4ea6dcb08 ("powerpc/mm: Enable mappings above 128TB") > Reported-by: Florian Weimer > Signed-off-by: Nicholas Piggin > --- > arch/powerpc/mm/slice.c | 50 ++++++++++++++++++++++++------------------------- > 1 file changed, 24 insertions(+), 26 deletions(-) > > diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c > index 45f6740dd407..3889201b560c 100644 > --- a/arch/powerpc/mm/slice.c > +++ b/arch/powerpc/mm/slice.c > @@ -96,7 +96,7 @@ static int slice_area_is_free(struct mm_struct *mm, unsigned long addr, > { > struct vm_area_struct *vma; > > - if ((mm->task_size - len) < addr) > + if ((mm->context.addr_limit - len) < addr) > return 0; > vma = find_vma(mm, addr); > return (!vma || (addr + len) <= vm_start_gap(vma)); > @@ -133,7 +133,7 @@ static void slice_mask_for_free(struct mm_struct *mm, struct slice_mask *ret) > if (!slice_low_has_vma(mm, i)) > ret->low_slices |= 1u << i; > > - if (mm->task_size <= SLICE_LOW_TOP) > + if (mm->context.addr_limit <= SLICE_LOW_TOP) > return; > > for (i = 0; i < GET_HIGH_SLICE_INDEX(mm->context.addr_limit); i++) > @@ -412,25 +412,31 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len, > struct slice_mask compat_mask; > int fixed = (flags & MAP_FIXED); > int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT); > + unsigned long page_size = 1UL << pshift; > struct mm_struct *mm = current->mm; > unsigned long newaddr; > unsigned long high_limit; > > - /* > - * Check if we need to expland slice area. > - */ > - if (unlikely(addr > mm->context.addr_limit && > - mm->context.addr_limit != TASK_SIZE)) { > - mm->context.addr_limit = TASK_SIZE; > + high_limit = DEFAULT_MAP_WINDOW; > + if (addr >= high_limit) > + high_limit = TASK_SIZE; > + > + if (len > high_limit) > + return -ENOMEM; > + if (len & (page_size - 1)) > + return -EINVAL; > + if (fixed) { > + if (addr & (page_size - 1)) > + return -EINVAL; > + if (addr > high_limit - len) > + return -ENOMEM; > + } > + > + if (high_limit > mm->context.addr_limit) { > + mm->context.addr_limit = high_limit; > on_each_cpu(slice_flush_segments, mm, 1); > } > - /* > - * This mmap request can allocate upt to 512TB > - */ > - if (addr > DEFAULT_MAP_WINDOW) > - high_limit = mm->context.addr_limit; > - else > - high_limit = DEFAULT_MAP_WINDOW; > + > /* > * init different masks > */ > @@ -446,27 +452,19 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len, > > /* Sanity checks */ > BUG_ON(mm->task_size == 0); > + BUG_ON(mm->context.addr_limit == 0); > VM_BUG_ON(radix_enabled()); > > slice_dbg("slice_get_unmapped_area(mm=%p, psize=%d...\n", mm, psize); > slice_dbg(" addr=%lx, len=%lx, flags=%lx, topdown=%d\n", > addr, len, flags, topdown); > > - if (len > mm->task_size) > - return -ENOMEM; > - if (len & ((1ul << pshift) - 1)) > - return -EINVAL; > - if (fixed && (addr & ((1ul << pshift) - 1))) > - return -EINVAL; > - if (fixed && addr > (mm->task_size - len)) > - return -ENOMEM; > - > /* If hint, make sure it matches our alignment restrictions */ > if (!fixed && addr) { > - addr = _ALIGN_UP(addr, 1ul << pshift); > + addr = _ALIGN_UP(addr, page_size); > slice_dbg(" aligned addr=%lx\n", addr); > /* Ignore hint if it's too large or overlaps a VMA */ > - if (addr > mm->task_size - len || > + if (addr > high_limit - len || > !slice_area_is_free(mm, addr, len)) > addr = 0; > } > -- > 2.15.0