| Message ID | 20221204013046.154960-4-bhe@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/vmalloc.c: allow vread() to read out vm_map_ram areas | expand |
Hi Baoquan,
I love your patch! Perhaps something to improve:
[auto build test WARNING on akpm-mm/mm-everything]
url: https://github.com/intel-lab-lkp/linux/commits/Baoquan-He/mm-vmalloc-c-allow-vread-to-read-out-vm_map_ram-areas/20221204-093322
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20221204013046.154960-4-bhe%40redhat.com
patch subject: [PATCH v1 3/7] mm/vmalloc.c: allow vread() to read out vm_map_ram areas
config: arm-randconfig-r046-20221204
compiler: arm-linux-gnueabi-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/0bcc4ce1e46418b86eb569175879081116649727
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Baoquan-He/mm-vmalloc-c-allow-vread-to-read-out-vm_map_ram-areas/20221204-093322
git checkout 0bcc4ce1e46418b86eb569175879081116649727
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
mm/vmalloc.c: In function 'vb_vread':
>> mm/vmalloc.c:3540:23: warning: variable 'offset' set but not used [-Wunused-but-set-variable]
3540 | unsigned long offset;
| ^~~~~~
vim +/offset +3540 mm/vmalloc.c
3535
3536 static void vb_vread(char *buf, char *addr, int count)
3537 {
3538 char *start;
3539 struct vmap_block *vb;
> 3540 unsigned long offset;
3541 unsigned int rs, re, n;
3542
3543 offset = ((unsigned long)addr & (VMAP_BLOCK_SIZE - 1)) >> PAGE_SHIFT;
3544 vb = xa_load(&vmap_blocks, addr_to_vb_idx((unsigned long)addr));
3545
3546 spin_lock(&vb->lock);
3547 if (bitmap_empty(vb->used_map, VMAP_BBMAP_BITS)) {
3548 spin_unlock(&vb->lock);
3549 memset(buf, 0, count);
3550 return;
3551 }
3552 for_each_set_bitrange(rs, re, vb->used_map, VMAP_BBMAP_BITS) {
3553 if (!count)
3554 break;
3555 start = vmap_block_vaddr(vb->va->va_start, rs);
3556 if (addr < start) {
3557 if (count == 0)
3558 break;
3559 *buf = '\0';
3560 buf++;
3561 addr++;
3562 count--;
3563 }
3564 n = (re - rs + 1) << PAGE_SHIFT;
3565 if (n > count)
3566 n = count;
3567 aligned_vread(buf, start, n);
3568
3569 buf += n;
3570 addr += n;
3571 count -= n;
3572 }
3573 spin_unlock(&vb->lock);
3574 }
3575
On 12/04/22 at 11:47am, kernel test robot wrote: > Hi Baoquan, > > I love your patch! Perhaps something to improve: > > [auto build test WARNING on akpm-mm/mm-everything] > > url: https://github.com/intel-lab-lkp/linux/commits/Baoquan-He/mm-vmalloc-c-allow-vread-to-read-out-vm_map_ram-areas/20221204-093322 > base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything > patch link: https://lore.kernel.org/r/20221204013046.154960-4-bhe%40redhat.com > patch subject: [PATCH v1 3/7] mm/vmalloc.c: allow vread() to read out vm_map_ram areas > config: arm-randconfig-r046-20221204 > compiler: arm-linux-gnueabi-gcc (GCC) 12.1.0 > reproduce (this is a W=1 build): > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > chmod +x ~/bin/make.cross > # https://github.com/intel-lab-lkp/linux/commit/0bcc4ce1e46418b86eb569175879081116649727 > git remote add linux-review https://github.com/intel-lab-lkp/linux > git fetch --no-tags linux-review Baoquan-He/mm-vmalloc-c-allow-vread-to-read-out-vm_map_ram-areas/20221204-093322 > git checkout 0bcc4ce1e46418b86eb569175879081116649727 > # save the config file > mkdir build_dir && cp config build_dir/.config > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash > > If you fix the issue, kindly add following tag where applicable > | Reported-by: kernel test robot <lkp@intel.com> > > All warnings (new ones prefixed by >>): > > mm/vmalloc.c: In function 'vb_vread': > >> mm/vmalloc.c:3540:23: warning: variable 'offset' set but not used [-Wunused-but-set-variable] > 3540 | unsigned long offset; > | ^~~~~~ Thanks. The local variable 'offset' is needed, the handling in vb_vread() need be improved to cover the case in which reading is started from dirty or free regions. I will add below change to v2. diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 78cae59170d8..6612914459cf 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3526,7 +3522,6 @@ static void vb_vread(char *buf, char *addr, int count) unsigned long offset; unsigned int rs, re, n; - offset = ((unsigned long)addr & (VMAP_BLOCK_SIZE - 1)) >> PAGE_SHIFT; vb = xa_load(&vmap_blocks, addr_to_vb_idx((unsigned long)addr)); spin_lock(&vb->lock); @@ -3547,16 +3542,22 @@ static void vb_vread(char *buf, char *addr, int count) addr++; count--; } - n = (re - rs + 1) << PAGE_SHIFT; + /*it could start reading from the middle of used region*/ + offset = offset_in_page(addr); + n = (re - rs + 1) << PAGE_SHIFT - offset; if (n > count) n = count; - aligned_vread(buf, start, n); + aligned_vread(buf, start+offset, n); buf += n; addr += n; count -= n; } spin_unlock(&vb->lock); + + /* zero-fill the left dirty or free regions */ + if (count) + memset(buf, 0, count); } /**
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index d6f376060d83..e6b46da3e044 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3519,6 +3519,46 @@ static int aligned_vread(char *buf, char *addr, unsigned long count) return copied; } +static void vb_vread(char *buf, char *addr, int count) +{ + char *start; + struct vmap_block *vb; + unsigned long offset; + unsigned int rs, re, n; + + offset = ((unsigned long)addr & (VMAP_BLOCK_SIZE - 1)) >> PAGE_SHIFT; + vb = xa_load(&vmap_blocks, addr_to_vb_idx((unsigned long)addr)); + + spin_lock(&vb->lock); + if (bitmap_empty(vb->used_map, VMAP_BBMAP_BITS)) { + spin_unlock(&vb->lock); + memset(buf, 0, count); + return; + } + for_each_set_bitrange(rs, re, vb->used_map, VMAP_BBMAP_BITS) { + if (!count) + break; + start = vmap_block_vaddr(vb->va->va_start, rs); + if (addr < start) { + if (count == 0) + break; + *buf = '\0'; + buf++; + addr++; + count--; + } + n = (re - rs + 1) << PAGE_SHIFT; + if (n > count) + n = count; + aligned_vread(buf, start, n); + + buf += n; + addr += n; + count -= n; + } + spin_unlock(&vb->lock); +} + /** * vread() - read vmalloc area in a safe way. * @buf: buffer for reading data @@ -3549,7 +3589,7 @@ long vread(char *buf, char *addr, unsigned long count) struct vm_struct *vm; char *vaddr, *buf_start = buf; unsigned long buflen = count; - unsigned long n; + unsigned long n, size, flags; addr = kasan_reset_tag(addr); @@ -3570,12 +3610,16 @@ long vread(char *buf, char *addr, unsigned long count) if (!count) break; - if (!va->vm) + vm = va->vm; + flags = va->flags & VMAP_FLAGS_MASK; + + if (!vm && !flags) continue; - vm = va->vm; - vaddr = (char *) vm->addr; - if (addr >= vaddr + get_vm_area_size(vm)) + vaddr = (char *) va->va_start; + size = flags ? va_size(va) : get_vm_area_size(vm); + + if (addr >= vaddr + size) continue; while (addr < vaddr) { if (count == 0) @@ -3585,10 +3629,13 @@ long vread(char *buf, char *addr, unsigned long count) addr++; count--; } - n = vaddr + get_vm_area_size(vm) - addr; + n = vaddr + size - addr; if (n > count) n = count; - if (!(vm->flags & VM_IOREMAP)) + + if ((flags & (VMAP_RAM|VMAP_BLOCK)) == (VMAP_RAM|VMAP_BLOCK)) + vb_vread(buf, addr, n); + else if ((flags & VMAP_RAM) || !(vm->flags & VM_IOREMAP)) aligned_vread(buf, addr, n); else /* IOREMAP area is treated as memory hole */ memset(buf, 0, n);
Currently, vread can read out vmalloc areas which is associated with a vm_struct. While this doesn't work for areas created by vm_map_ram() interface because it doesn't have an associated vm_struct. Then in vread(), these areas will be skipped. Here, add a new function vb_vread() to read out areas managed by vmap_block specifically. Then recognize vm_map_ram areas via vmap->flags and handle them respectively. Signed-off-by: Baoquan He <bhe@redhat.com> --- mm/vmalloc.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 54 insertions(+), 7 deletions(-)