tree: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable head: 39aca4f17e02ee4076b6ab327577c9b1be23775d commit: d9cab54f77377439e766e1c5916f79ec2ee27a6c [288/290] mm: vmalloc: convert vread() to vread_iter() config: i386-randconfig-a002 (https://download.01.org/0day-ci/archive/20230323/202303231055.DeninwHS-lkp@xxxxxxxxx/config) compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1) 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://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/commit/?id=d9cab54f77377439e766e1c5916f79ec2ee27a6c git remote add akpm-mm https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git git fetch --no-tags akpm-mm mm-unstable git checkout d9cab54f77377439e766e1c5916f79ec2ee27a6c # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 olddefconfig COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash If you fix the issue, kindly add following tag where applicable | Reported-by: kernel test robot <lkp@xxxxxxxxx> | Link: https://lore.kernel.org/oe-kbuild-all/202303231055.DeninwHS-lkp@xxxxxxxxx/ All warnings (new ones prefixed by >>): >> mm/vmalloc.c:3448:8: warning: no previous prototype for function 'zero_iter' [-Wmissing-prototypes] size_t zero_iter(struct iov_iter *iter, size_t count) ^ mm/vmalloc.c:3448:1: note: declare 'static' if the function is not intended to be used outside of this translation unit size_t zero_iter(struct iov_iter *iter, size_t count) ^ static >> mm/vmalloc.c:3543:6: warning: variable 'remains' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (bitmap_empty(vb->used_map, VMAP_BBMAP_BITS)) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ mm/vmalloc.c:3587:17: note: uninitialized use occurs here return count - remains + zero_iter(iter, remains); ^~~~~~~ mm/vmalloc.c:3543:2: note: remove the 'if' if its condition is always false if (bitmap_empty(vb->used_map, VMAP_BBMAP_BITS)) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ mm/vmalloc.c:3539:6: warning: variable 'remains' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (!vb) ^~~ mm/vmalloc.c:3587:17: note: uninitialized use occurs here return count - remains + zero_iter(iter, remains); ^~~~~~~ mm/vmalloc.c:3539:2: note: remove the 'if' if its condition is always false if (!vb) ^~~~~~~~ mm/vmalloc.c:3524:16: note: initialize the variable 'remains' to silence this warning size_t remains, n; ^ = 0 3 warnings generated. vim +/zero_iter +3448 mm/vmalloc.c 3442 3443 /* 3444 * Atomically zero bytes in the iterator. 3445 * 3446 * Returns the number of zeroed bytes. 3447 */ > 3448 size_t zero_iter(struct iov_iter *iter, size_t count) 3449 { 3450 size_t remains = count; 3451 3452 while (remains > 0) { 3453 size_t num, copied; 3454 3455 num = remains < PAGE_SIZE ? remains : PAGE_SIZE; 3456 copied = copy_page_to_iter_atomic(ZERO_PAGE(0), 0, num, iter); 3457 remains -= copied; 3458 3459 if (copied < num) 3460 break; 3461 } 3462 3463 return count - remains; 3464 } 3465 3466 /* 3467 * small helper routine, copy contents to iter from addr. 3468 * If the page is not present, fill zero. 3469 * 3470 * Returns the number of copied bytes. 3471 */ 3472 static size_t aligned_vread_iter(struct iov_iter *iter, 3473 const char *addr, size_t count) 3474 { 3475 size_t remains = count; 3476 struct page *page; 3477 3478 while (remains > 0) { 3479 unsigned long offset, length; 3480 size_t copied = 0; 3481 3482 offset = offset_in_page(addr); 3483 length = PAGE_SIZE - offset; 3484 if (length > remains) 3485 length = remains; 3486 page = vmalloc_to_page(addr); 3487 /* 3488 * To do safe access to this _mapped_ area, we need lock. But 3489 * adding lock here means that we need to add overhead of 3490 * vmalloc()/vfree() calls for this _debug_ interface, rarely 3491 * used. Instead of that, we'll use an local mapping via 3492 * copy_page_to_iter_atomic() and accept a small overhead in 3493 * this access function. 3494 */ 3495 if (page) 3496 copied = copy_page_to_iter_atomic(page, offset, length, 3497 iter); 3498 3499 /* Zero anything we were unable to copy. */ 3500 copied += zero_iter(iter, length - copied); 3501 3502 addr += copied; 3503 remains -= copied; 3504 3505 if (copied != length) 3506 break; 3507 } 3508 3509 return count - remains; 3510 } 3511 3512 /* 3513 * Read from a vm_map_ram region of memory. 3514 * 3515 * Returns the number of copied bytes. 3516 */ 3517 static size_t vmap_ram_vread_iter(struct iov_iter *iter, const char *addr, 3518 size_t count, unsigned long flags) 3519 { 3520 char *start; 3521 struct vmap_block *vb; 3522 unsigned long offset; 3523 unsigned int rs, re; 3524 size_t remains, n; 3525 3526 /* 3527 * If it's area created by vm_map_ram() interface directly, but 3528 * not further subdividing and delegating management to vmap_block, 3529 * handle it here. 3530 */ 3531 if (!(flags & VMAP_BLOCK)) 3532 return aligned_vread_iter(iter, addr, count); 3533 3534 /* 3535 * Area is split into regions and tracked with vmap_block, read out 3536 * each region and zero fill the hole between regions. 3537 */ 3538 vb = xa_load(&vmap_blocks, addr_to_vb_idx((unsigned long)addr)); 3539 if (!vb) 3540 goto finished_zero; 3541 3542 spin_lock(&vb->lock); > 3543 if (bitmap_empty(vb->used_map, VMAP_BBMAP_BITS)) { 3544 spin_unlock(&vb->lock); 3545 goto finished_zero; 3546 } 3547 3548 remains = count; 3549 for_each_set_bitrange(rs, re, vb->used_map, VMAP_BBMAP_BITS) { 3550 size_t copied; 3551 3552 if (remains == 0) 3553 goto finished; 3554 3555 start = vmap_block_vaddr(vb->va->va_start, rs); 3556 3557 if (addr < start) { 3558 size_t to_zero = min_t(size_t, start - addr, remains); 3559 size_t zeroed = zero_iter(iter, to_zero); 3560 3561 addr += zeroed; 3562 remains -= zeroed; 3563 3564 if (remains == 0 || zeroed != to_zero) 3565 goto finished; 3566 } 3567 3568 /*it could start reading from the middle of used region*/ 3569 offset = offset_in_page(addr); 3570 n = ((re - rs + 1) << PAGE_SHIFT) - offset; 3571 if (n > remains) 3572 n = remains; 3573 3574 copied = aligned_vread_iter(iter, start + offset, n); 3575 3576 addr += copied; 3577 remains -= copied; 3578 3579 if (copied != n) 3580 goto finished; 3581 } 3582 3583 spin_unlock(&vb->lock); 3584 3585 finished_zero: 3586 /* zero-fill the left dirty or free regions */ 3587 return count - remains + zero_iter(iter, remains); 3588 finished: 3589 /* We couldn't copy/zero everything */ 3590 spin_unlock(&vb->lock); 3591 return count - remains; 3592 } 3593 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests
