| Message ID | 20210122154547.502685-1-matthew.auld@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/i915/buddy: document the unused header bits | expand |
Quoting Matthew Auld (2021-01-22 15:45:46) > The largest possible order is (63-12), given that our min chunk size is > 4K. With that we should only need at most 6 bits to represent all > possible orders, giving us back 4 bits for other potential uses. Include > a simple selftest to verify this. > > Signed-off-by: Matthew Auld <matthew.auld@intel.com> > --- > drivers/gpu/drm/i915/i915_buddy.c | 3 ++ > drivers/gpu/drm/i915/i915_buddy.h | 7 ++- > drivers/gpu/drm/i915/selftests/i915_buddy.c | 47 +++++++++++++++++++++ > 3 files changed, 55 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_buddy.c b/drivers/gpu/drm/i915/i915_buddy.c > index 20babbdb297d..650613ae2a7b 100644 > --- a/drivers/gpu/drm/i915/i915_buddy.c > +++ b/drivers/gpu/drm/i915/i915_buddy.c > @@ -56,6 +56,9 @@ static struct i915_buddy_block *i915_block_alloc(struct i915_buddy_block *parent > block->header |= order; > block->parent = parent; > > + GEM_BUG_ON(block->header & I915_BUDDY_HEADER_UNUSED); Ok... > + GEM_BUG_ON(order > I915_BUDDY_MAX_ORDER); But this is really a contract on the incoming parameter and so should be at the start of the function. GEM_BUG_ON(block->header...) is a contract on our output. > + > return block; > } > > diff --git a/drivers/gpu/drm/i915/i915_buddy.h b/drivers/gpu/drm/i915/i915_buddy.h > index ed41f3507cdc..d37e03587637 100644 > --- a/drivers/gpu/drm/i915/i915_buddy.h > +++ b/drivers/gpu/drm/i915/i915_buddy.h > @@ -15,7 +15,9 @@ struct i915_buddy_block { > #define I915_BUDDY_ALLOCATED (1 << 10) > #define I915_BUDDY_FREE (2 << 10) > #define I915_BUDDY_SPLIT (3 << 10) > -#define I915_BUDDY_HEADER_ORDER GENMASK_ULL(9, 0) > +/* Free to be used, if needed in the future */ > +#define I915_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6) > +#define I915_BUDDY_HEADER_ORDER GENMASK_ULL(5, 0) > u64 header; > > struct i915_buddy_block *left; > @@ -34,7 +36,8 @@ struct i915_buddy_block { > struct list_head tmp_link; > }; > > -#define I915_BUDDY_MAX_ORDER I915_BUDDY_HEADER_ORDER > +/* Order-zero must be at least PAGE_SIZE */ > +#define I915_BUDDY_MAX_ORDER (63 - 12) Can we replace 12 with an ilog2() ? PAGE_SIZE is mentioned as the lower limit, so PAGE_SHIFT? > /* > * Binary Buddy System. > diff --git a/drivers/gpu/drm/i915/selftests/i915_buddy.c b/drivers/gpu/drm/i915/selftests/i915_buddy.c > index 632b912b0bc9..39c470a0e28d 100644 > --- a/drivers/gpu/drm/i915/selftests/i915_buddy.c > +++ b/drivers/gpu/drm/i915/selftests/i915_buddy.c > @@ -727,6 +727,52 @@ static int igt_buddy_alloc_range(void *arg) > return err; > } > > +static int igt_buddy_alloc_limit(void *arg) > +{ > + struct i915_buddy_block *block; > + struct i915_buddy_mm mm; > + const u64 size = U64_MAX; > + int err; > + > + err = i915_buddy_init(&mm, size, PAGE_SIZE); Create the biggest region possible. > + if (err) > + return err; > + > + if (mm.max_order != I915_BUDDY_MAX_ORDER) { Check that we made it as big as possible. > + pr_err("mm.max_order(%d) != %d\n", > + mm.max_order, I915_BUDDY_MAX_ORDER); > + err = -EINVAL; > + goto out_fini; > + } > + > + block = i915_buddy_alloc(&mm, mm.max_order); Allocate the largest single block. > + if (IS_ERR(block)) { > + err = PTR_ERR(block); > + goto out_fini; > + } > + > + if (i915_buddy_block_order(block) != I915_BUDDY_MAX_ORDER) { Check that it is as large we tried to allocate... But it should be mm.max_order to check the actual limits in place. > + pr_err("block order(%d) != %d\n", > + i915_buddy_block_order(block), I915_BUDDY_MAX_ORDER); > + err = -EINVAL; > + goto out_free; > + } > + > + if (i915_buddy_block_size(&mm, block) != rounddown_pow_of_two(size)) { Which is the largest buddy block within the range. Hmm, this I don't think follows the I915_BUDDY_MAX_ORDER constraint. What if we reduce the MAX_ORDER to be say 48? Then the buddy block will correctly be (1<<48). So I think you just want size() == BIT_ULL(mm.max_order) With those questions addressed however you see fit, Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> -Chris
Hi Matthew,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on drm-intel/for-linux-next]
[also build test WARNING on drm-tip/drm-tip v5.11-rc5 next-20210122]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Matthew-Auld/drm-i915-buddy-document-the-unused-header-bits/20210125-111101
base: git://anongit.freedesktop.org/drm-intel for-linux-next
config: i386-randconfig-a012-20210125 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-20) 9.3.0
reproduce (this is a W=1 build):
# https://github.com/0day-ci/linux/commit/9d12a23788459bd678c0f5979acaaf94a88d808c
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Matthew-Auld/drm-i915-buddy-document-the-unused-header-bits/20210125-111101
git checkout 9d12a23788459bd678c0f5979acaaf94a88d808c
# save the attached .config to linux build tree
make W=1 ARCH=i386
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
In file included from include/asm-generic/bug.h:5,
from arch/x86/include/asm/bug.h:93,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from include/linux/kmemleak.h:12,
from drivers/gpu/drm/i915/i915_buddy.c:6:
drivers/gpu/drm/i915/selftests/i915_buddy.c: In function 'igt_buddy_alloc_limit':
>> include/linux/log2.h:194:8: warning: left shift count >= width of type [-Wshift-count-overflow]
194 | (1UL << ilog2(n))) : \
| ^~
include/linux/compiler.h:58:52: note: in definition of macro '__trace_if_var'
58 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
| ^~~~
drivers/gpu/drm/i915/selftests/i915_buddy.c:761:2: note: in expansion of macro 'if'
761 | if (i915_buddy_block_size(&mm, block) != rounddown_pow_of_two(size)) {
| ^~
drivers/gpu/drm/i915/selftests/i915_buddy.c:761:43: note: in expansion of macro 'rounddown_pow_of_two'
761 | if (i915_buddy_block_size(&mm, block) != rounddown_pow_of_two(size)) {
| ^~~~~~~~~~~~~~~~~~~~
>> include/linux/log2.h:194:8: warning: left shift count >= width of type [-Wshift-count-overflow]
194 | (1UL << ilog2(n))) : \
| ^~
include/linux/compiler.h:69:3: note: in definition of macro '__trace_if_value'
69 | (cond) ? \
| ^~~~
include/linux/compiler.h:56:28: note: in expansion of macro '__trace_if_var'
56 | #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
| ^~~~~~~~~~~~~~
drivers/gpu/drm/i915/selftests/i915_buddy.c:761:2: note: in expansion of macro 'if'
761 | if (i915_buddy_block_size(&mm, block) != rounddown_pow_of_two(size)) {
| ^~
drivers/gpu/drm/i915/selftests/i915_buddy.c:761:43: note: in expansion of macro 'rounddown_pow_of_two'
761 | if (i915_buddy_block_size(&mm, block) != rounddown_pow_of_two(size)) {
| ^~~~~~~~~~~~~~~~~~~~
In file included from include/linux/kernel.h:12,
from include/asm-generic/bug.h:20,
from arch/x86/include/asm/bug.h:93,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from include/linux/kmemleak.h:12,
from drivers/gpu/drm/i915/i915_buddy.c:6:
>> include/linux/log2.h:194:8: warning: left shift count >= width of type [-Wshift-count-overflow]
194 | (1UL << ilog2(n))) : \
| ^~
include/linux/printk.h:343:33: note: in expansion of macro 'rounddown_pow_of_two'
343 | printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
| ^~~~~~~~~~~
drivers/gpu/drm/i915/selftests/i915_buddy.c:762:3: note: in expansion of macro 'pr_err'
762 | pr_err("block size(%llu) != %lu\n",
| ^~~~~~
vim +194 include/linux/log2.h
b311e921b385b5a Robert P. J. Day 2007-10-16 69
f0d1b0b30d250a0 David Howells 2006-12-08 70 /**
dbef91ec5482239 Martin Wilck 2018-04-18 71 * const_ilog2 - log base 2 of 32-bit or a 64-bit constant unsigned value
a1c4d24e02d093e Randy Dunlap 2017-09-30 72 * @n: parameter
f0d1b0b30d250a0 David Howells 2006-12-08 73 *
dbef91ec5482239 Martin Wilck 2018-04-18 74 * Use this where sparse expects a true constant expression, e.g. for array
dbef91ec5482239 Martin Wilck 2018-04-18 75 * indices.
f0d1b0b30d250a0 David Howells 2006-12-08 76 */
dbef91ec5482239 Martin Wilck 2018-04-18 77 #define const_ilog2(n) \
f0d1b0b30d250a0 David Howells 2006-12-08 78 ( \
f0d1b0b30d250a0 David Howells 2006-12-08 79 __builtin_constant_p(n) ? ( \
474c90156c8dcc2 Linus Torvalds 2017-03-02 80 (n) < 2 ? 0 : \
f0d1b0b30d250a0 David Howells 2006-12-08 81 (n) & (1ULL << 63) ? 63 : \
f0d1b0b30d250a0 David Howells 2006-12-08 82 (n) & (1ULL << 62) ? 62 : \
f0d1b0b30d250a0 David Howells 2006-12-08 83 (n) & (1ULL << 61) ? 61 : \
f0d1b0b30d250a0 David Howells 2006-12-08 84 (n) & (1ULL << 60) ? 60 : \
f0d1b0b30d250a0 David Howells 2006-12-08 85 (n) & (1ULL << 59) ? 59 : \
f0d1b0b30d250a0 David Howells 2006-12-08 86 (n) & (1ULL << 58) ? 58 : \
f0d1b0b30d250a0 David Howells 2006-12-08 87 (n) & (1ULL << 57) ? 57 : \
f0d1b0b30d250a0 David Howells 2006-12-08 88 (n) & (1ULL << 56) ? 56 : \
f0d1b0b30d250a0 David Howells 2006-12-08 89 (n) & (1ULL << 55) ? 55 : \
f0d1b0b30d250a0 David Howells 2006-12-08 90 (n) & (1ULL << 54) ? 54 : \
f0d1b0b30d250a0 David Howells 2006-12-08 91 (n) & (1ULL << 53) ? 53 : \
f0d1b0b30d250a0 David Howells 2006-12-08 92 (n) & (1ULL << 52) ? 52 : \
f0d1b0b30d250a0 David Howells 2006-12-08 93 (n) & (1ULL << 51) ? 51 : \
f0d1b0b30d250a0 David Howells 2006-12-08 94 (n) & (1ULL << 50) ? 50 : \
f0d1b0b30d250a0 David Howells 2006-12-08 95 (n) & (1ULL << 49) ? 49 : \
f0d1b0b30d250a0 David Howells 2006-12-08 96 (n) & (1ULL << 48) ? 48 : \
f0d1b0b30d250a0 David Howells 2006-12-08 97 (n) & (1ULL << 47) ? 47 : \
f0d1b0b30d250a0 David Howells 2006-12-08 98 (n) & (1ULL << 46) ? 46 : \
f0d1b0b30d250a0 David Howells 2006-12-08 99 (n) & (1ULL << 45) ? 45 : \
f0d1b0b30d250a0 David Howells 2006-12-08 100 (n) & (1ULL << 44) ? 44 : \
f0d1b0b30d250a0 David Howells 2006-12-08 101 (n) & (1ULL << 43) ? 43 : \
f0d1b0b30d250a0 David Howells 2006-12-08 102 (n) & (1ULL << 42) ? 42 : \
f0d1b0b30d250a0 David Howells 2006-12-08 103 (n) & (1ULL << 41) ? 41 : \
f0d1b0b30d250a0 David Howells 2006-12-08 104 (n) & (1ULL << 40) ? 40 : \
f0d1b0b30d250a0 David Howells 2006-12-08 105 (n) & (1ULL << 39) ? 39 : \
f0d1b0b30d250a0 David Howells 2006-12-08 106 (n) & (1ULL << 38) ? 38 : \
f0d1b0b30d250a0 David Howells 2006-12-08 107 (n) & (1ULL << 37) ? 37 : \
f0d1b0b30d250a0 David Howells 2006-12-08 108 (n) & (1ULL << 36) ? 36 : \
f0d1b0b30d250a0 David Howells 2006-12-08 109 (n) & (1ULL << 35) ? 35 : \
f0d1b0b30d250a0 David Howells 2006-12-08 110 (n) & (1ULL << 34) ? 34 : \
f0d1b0b30d250a0 David Howells 2006-12-08 111 (n) & (1ULL << 33) ? 33 : \
f0d1b0b30d250a0 David Howells 2006-12-08 112 (n) & (1ULL << 32) ? 32 : \
f0d1b0b30d250a0 David Howells 2006-12-08 113 (n) & (1ULL << 31) ? 31 : \
f0d1b0b30d250a0 David Howells 2006-12-08 114 (n) & (1ULL << 30) ? 30 : \
f0d1b0b30d250a0 David Howells 2006-12-08 115 (n) & (1ULL << 29) ? 29 : \
f0d1b0b30d250a0 David Howells 2006-12-08 116 (n) & (1ULL << 28) ? 28 : \
f0d1b0b30d250a0 David Howells 2006-12-08 117 (n) & (1ULL << 27) ? 27 : \
f0d1b0b30d250a0 David Howells 2006-12-08 118 (n) & (1ULL << 26) ? 26 : \
f0d1b0b30d250a0 David Howells 2006-12-08 119 (n) & (1ULL << 25) ? 25 : \
f0d1b0b30d250a0 David Howells 2006-12-08 120 (n) & (1ULL << 24) ? 24 : \
f0d1b0b30d250a0 David Howells 2006-12-08 121 (n) & (1ULL << 23) ? 23 : \
f0d1b0b30d250a0 David Howells 2006-12-08 122 (n) & (1ULL << 22) ? 22 : \
f0d1b0b30d250a0 David Howells 2006-12-08 123 (n) & (1ULL << 21) ? 21 : \
f0d1b0b30d250a0 David Howells 2006-12-08 124 (n) & (1ULL << 20) ? 20 : \
f0d1b0b30d250a0 David Howells 2006-12-08 125 (n) & (1ULL << 19) ? 19 : \
f0d1b0b30d250a0 David Howells 2006-12-08 126 (n) & (1ULL << 18) ? 18 : \
f0d1b0b30d250a0 David Howells 2006-12-08 127 (n) & (1ULL << 17) ? 17 : \
f0d1b0b30d250a0 David Howells 2006-12-08 128 (n) & (1ULL << 16) ? 16 : \
f0d1b0b30d250a0 David Howells 2006-12-08 129 (n) & (1ULL << 15) ? 15 : \
f0d1b0b30d250a0 David Howells 2006-12-08 130 (n) & (1ULL << 14) ? 14 : \
f0d1b0b30d250a0 David Howells 2006-12-08 131 (n) & (1ULL << 13) ? 13 : \
f0d1b0b30d250a0 David Howells 2006-12-08 132 (n) & (1ULL << 12) ? 12 : \
f0d1b0b30d250a0 David Howells 2006-12-08 133 (n) & (1ULL << 11) ? 11 : \
f0d1b0b30d250a0 David Howells 2006-12-08 134 (n) & (1ULL << 10) ? 10 : \
f0d1b0b30d250a0 David Howells 2006-12-08 135 (n) & (1ULL << 9) ? 9 : \
f0d1b0b30d250a0 David Howells 2006-12-08 136 (n) & (1ULL << 8) ? 8 : \
f0d1b0b30d250a0 David Howells 2006-12-08 137 (n) & (1ULL << 7) ? 7 : \
f0d1b0b30d250a0 David Howells 2006-12-08 138 (n) & (1ULL << 6) ? 6 : \
f0d1b0b30d250a0 David Howells 2006-12-08 139 (n) & (1ULL << 5) ? 5 : \
f0d1b0b30d250a0 David Howells 2006-12-08 140 (n) & (1ULL << 4) ? 4 : \
f0d1b0b30d250a0 David Howells 2006-12-08 141 (n) & (1ULL << 3) ? 3 : \
f0d1b0b30d250a0 David Howells 2006-12-08 142 (n) & (1ULL << 2) ? 2 : \
474c90156c8dcc2 Linus Torvalds 2017-03-02 143 1) : \
dbef91ec5482239 Martin Wilck 2018-04-18 144 -1)
dbef91ec5482239 Martin Wilck 2018-04-18 145
dbef91ec5482239 Martin Wilck 2018-04-18 146 /**
dbef91ec5482239 Martin Wilck 2018-04-18 147 * ilog2 - log base 2 of 32-bit or a 64-bit unsigned value
dbef91ec5482239 Martin Wilck 2018-04-18 148 * @n: parameter
dbef91ec5482239 Martin Wilck 2018-04-18 149 *
dbef91ec5482239 Martin Wilck 2018-04-18 150 * constant-capable log of base 2 calculation
dbef91ec5482239 Martin Wilck 2018-04-18 151 * - this can be used to initialise global variables from constant data, hence
dbef91ec5482239 Martin Wilck 2018-04-18 152 * the massive ternary operator construction
dbef91ec5482239 Martin Wilck 2018-04-18 153 *
dbef91ec5482239 Martin Wilck 2018-04-18 154 * selects the appropriately-sized optimised version depending on sizeof(n)
dbef91ec5482239 Martin Wilck 2018-04-18 155 */
dbef91ec5482239 Martin Wilck 2018-04-18 156 #define ilog2(n) \
dbef91ec5482239 Martin Wilck 2018-04-18 157 ( \
dbef91ec5482239 Martin Wilck 2018-04-18 158 __builtin_constant_p(n) ? \
2f78788b55baa34 Jakub Jelinek 2020-12-15 159 ((n) < 2 ? 0 : \
2f78788b55baa34 Jakub Jelinek 2020-12-15 160 63 - __builtin_clzll(n)) : \
f0d1b0b30d250a0 David Howells 2006-12-08 161 (sizeof(n) <= 4) ? \
f0d1b0b30d250a0 David Howells 2006-12-08 162 __ilog2_u32(n) : \
f0d1b0b30d250a0 David Howells 2006-12-08 163 __ilog2_u64(n) \
f0d1b0b30d250a0 David Howells 2006-12-08 164 )
f0d1b0b30d250a0 David Howells 2006-12-08 165
312a0c170945b49 David Howells 2006-12-08 166 /**
312a0c170945b49 David Howells 2006-12-08 167 * roundup_pow_of_two - round the given value up to nearest power of two
a1c4d24e02d093e Randy Dunlap 2017-09-30 168 * @n: parameter
312a0c170945b49 David Howells 2006-12-08 169 *
6fb189c2a4f3bea Robert P. J. Day 2007-02-17 170 * round the given value up to the nearest power of two
312a0c170945b49 David Howells 2006-12-08 171 * - the result is undefined when n == 0
312a0c170945b49 David Howells 2006-12-08 172 * - this can be used to initialise global variables from constant data
312a0c170945b49 David Howells 2006-12-08 173 */
312a0c170945b49 David Howells 2006-12-08 174 #define roundup_pow_of_two(n) \
312a0c170945b49 David Howells 2006-12-08 175 ( \
312a0c170945b49 David Howells 2006-12-08 176 __builtin_constant_p(n) ? ( \
428fc0aff4e5939 Jason Gunthorpe 2020-09-04 177 ((n) == 1) ? 1 : \
312a0c170945b49 David Howells 2006-12-08 178 (1UL << (ilog2((n) - 1) + 1)) \
312a0c170945b49 David Howells 2006-12-08 179 ) : \
312a0c170945b49 David Howells 2006-12-08 180 __roundup_pow_of_two(n) \
312a0c170945b49 David Howells 2006-12-08 181 )
312a0c170945b49 David Howells 2006-12-08 182
b311e921b385b5a Robert P. J. Day 2007-10-16 183 /**
b311e921b385b5a Robert P. J. Day 2007-10-16 184 * rounddown_pow_of_two - round the given value down to nearest power of two
a1c4d24e02d093e Randy Dunlap 2017-09-30 185 * @n: parameter
b311e921b385b5a Robert P. J. Day 2007-10-16 186 *
b311e921b385b5a Robert P. J. Day 2007-10-16 187 * round the given value down to the nearest power of two
b311e921b385b5a Robert P. J. Day 2007-10-16 188 * - the result is undefined when n == 0
b311e921b385b5a Robert P. J. Day 2007-10-16 189 * - this can be used to initialise global variables from constant data
b311e921b385b5a Robert P. J. Day 2007-10-16 190 */
b311e921b385b5a Robert P. J. Day 2007-10-16 191 #define rounddown_pow_of_two(n) \
b311e921b385b5a Robert P. J. Day 2007-10-16 192 ( \
b311e921b385b5a Robert P. J. Day 2007-10-16 193 __builtin_constant_p(n) ? ( \
b311e921b385b5a Robert P. J. Day 2007-10-16 @194 (1UL << ilog2(n))) : \
b311e921b385b5a Robert P. J. Day 2007-10-16 195 __rounddown_pow_of_two(n) \
b311e921b385b5a Robert P. J. Day 2007-10-16 196 )
b311e921b385b5a Robert P. J. Day 2007-10-16 197
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff --git a/drivers/gpu/drm/i915/i915_buddy.c b/drivers/gpu/drm/i915/i915_buddy.c index 20babbdb297d..650613ae2a7b 100644 --- a/drivers/gpu/drm/i915/i915_buddy.c +++ b/drivers/gpu/drm/i915/i915_buddy.c @@ -56,6 +56,9 @@ static struct i915_buddy_block *i915_block_alloc(struct i915_buddy_block *parent block->header |= order; block->parent = parent; + GEM_BUG_ON(block->header & I915_BUDDY_HEADER_UNUSED); + GEM_BUG_ON(order > I915_BUDDY_MAX_ORDER); + return block; } diff --git a/drivers/gpu/drm/i915/i915_buddy.h b/drivers/gpu/drm/i915/i915_buddy.h index ed41f3507cdc..d37e03587637 100644 --- a/drivers/gpu/drm/i915/i915_buddy.h +++ b/drivers/gpu/drm/i915/i915_buddy.h @@ -15,7 +15,9 @@ struct i915_buddy_block { #define I915_BUDDY_ALLOCATED (1 << 10) #define I915_BUDDY_FREE (2 << 10) #define I915_BUDDY_SPLIT (3 << 10) -#define I915_BUDDY_HEADER_ORDER GENMASK_ULL(9, 0) +/* Free to be used, if needed in the future */ +#define I915_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6) +#define I915_BUDDY_HEADER_ORDER GENMASK_ULL(5, 0) u64 header; struct i915_buddy_block *left; @@ -34,7 +36,8 @@ struct i915_buddy_block { struct list_head tmp_link; }; -#define I915_BUDDY_MAX_ORDER I915_BUDDY_HEADER_ORDER +/* Order-zero must be at least PAGE_SIZE */ +#define I915_BUDDY_MAX_ORDER (63 - 12) /* * Binary Buddy System. diff --git a/drivers/gpu/drm/i915/selftests/i915_buddy.c b/drivers/gpu/drm/i915/selftests/i915_buddy.c index 632b912b0bc9..39c470a0e28d 100644 --- a/drivers/gpu/drm/i915/selftests/i915_buddy.c +++ b/drivers/gpu/drm/i915/selftests/i915_buddy.c @@ -727,6 +727,52 @@ static int igt_buddy_alloc_range(void *arg) return err; } +static int igt_buddy_alloc_limit(void *arg) +{ + struct i915_buddy_block *block; + struct i915_buddy_mm mm; + const u64 size = U64_MAX; + int err; + + err = i915_buddy_init(&mm, size, PAGE_SIZE); + if (err) + return err; + + if (mm.max_order != I915_BUDDY_MAX_ORDER) { + pr_err("mm.max_order(%d) != %d\n", + mm.max_order, I915_BUDDY_MAX_ORDER); + err = -EINVAL; + goto out_fini; + } + + block = i915_buddy_alloc(&mm, mm.max_order); + if (IS_ERR(block)) { + err = PTR_ERR(block); + goto out_fini; + } + + if (i915_buddy_block_order(block) != I915_BUDDY_MAX_ORDER) { + pr_err("block order(%d) != %d\n", + i915_buddy_block_order(block), I915_BUDDY_MAX_ORDER); + err = -EINVAL; + goto out_free; + } + + if (i915_buddy_block_size(&mm, block) != rounddown_pow_of_two(size)) { + pr_err("block size(%llu) != %lu\n", + i915_buddy_block_size(&mm, block), + rounddown_pow_of_two(size)); + err = -EINVAL; + goto out_free; + } + +out_free: + i915_buddy_free(&mm, block); +out_fini: + i915_buddy_fini(&mm); + return err; +} + int i915_buddy_mock_selftests(void) { static const struct i915_subtest tests[] = { @@ -735,6 +781,7 @@ int i915_buddy_mock_selftests(void) SUBTEST(igt_buddy_alloc_pathological), SUBTEST(igt_buddy_alloc_smoke), SUBTEST(igt_buddy_alloc_range), + SUBTEST(igt_buddy_alloc_limit), }; return i915_subtests(tests, NULL);
The largest possible order is (63-12), given that our min chunk size is 4K. With that we should only need at most 6 bits to represent all possible orders, giving us back 4 bits for other potential uses. Include a simple selftest to verify this. Signed-off-by: Matthew Auld <matthew.auld@intel.com> --- drivers/gpu/drm/i915/i915_buddy.c | 3 ++ drivers/gpu/drm/i915/i915_buddy.h | 7 ++- drivers/gpu/drm/i915/selftests/i915_buddy.c | 47 +++++++++++++++++++++ 3 files changed, 55 insertions(+), 2 deletions(-)