/* * Copyright 2009 Red Hat Inc. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. * * Authors: Dave Airlie * Christian König */ #ifndef DRM_FIXED_H #define DRM_FIXED_H #include typedef union dfixed { u32 full; } fixed20_12; #define dfixed_const(A) (u32)(((A) << 12))/* + ((B + 0.000122)*4096)) */ #define dfixed_const_half(A) (u32)(((A) << 12) + 2048) #define dfixed_const_666(A) (u32)(((A) << 12) + 2731) #define dfixed_const_8(A) (u32)(((A) << 12) + 3277) #define dfixed_mul(A, B) ((u64)((u64)(A).full * (B).full + 2048) >> 12) #define dfixed_init(A) { .full = dfixed_const((A)) } #define dfixed_init_half(A) { .full = dfixed_const_half((A)) } #define dfixed_trunc(A) ((A).full >> 12) #define dfixed_frac(A) ((A).full & ((1 << 12) - 1)) static inline u32 dfixed_floor(fixed20_12 A) { u32 non_frac = dfixed_trunc(A); return dfixed_const(non_frac); } static inline u32 dfixed_ceil(fixed20_12 A) { u32 non_frac = dfixed_trunc(A); if (A.full > dfixed_const(non_frac)) return dfixed_const(non_frac + 1); else return dfixed_const(non_frac); } static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B) { u64 tmp = ((u64)A.full << 13); do_div(tmp, B.full); tmp += 1; tmp /= 2; return lower_32_bits(tmp); } #define DRM_FIXED_POINT 32 #define DRM_FIXED_ONE (1ULL << DRM_FIXED_POINT) #define DRM_FIXED_DECIMAL_MASK (DRM_FIXED_ONE - 1) #define DRM_FIXED_DIGITS_MASK (~DRM_FIXED_DECIMAL_MASK) #define DRM_FIXED_EPSILON 1LL #define DRM_FIXED_ALMOST_ONE (DRM_FIXED_ONE - DRM_FIXED_EPSILON) static inline s64 drm_int2fixp(int a) { return ((s64)a) << DRM_FIXED_POINT; } static inline int drm_fixp2int(s64 a) { return ((s64)a) >> DRM_FIXED_POINT; } static inline int drm_fixp2int_ceil(s64 a) { if (a > 0) return drm_fixp2int(a + DRM_FIXED_ALMOST_ONE); else return drm_fixp2int(a - DRM_FIXED_ALMOST_ONE); } static inline unsigned drm_fixp_msbset(s64 a) { unsigned shift, sign = (a >> 63) & 1; for (shift = 62; shift > 0; --shift) if (((a >> shift) & 1) != sign) return shift; return 0; } static inline s64 drm_fixp_mul(s64 a, s64 b) { unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b); s64 result; if (shift > 61) { shift = shift - 61; a >>= (shift >> 1) + (shift & 1); b >>= shift >> 1; } else shift = 0; result = a * b; if (shift > DRM_FIXED_POINT) return result << (shift - DRM_FIXED_POINT); if (shift < DRM_FIXED_POINT) return result >> (DRM_FIXED_POINT - shift); return result; } static inline s64 drm_fixp_div(s64 a, s64 b) { unsigned shift = 62 - drm_fixp_msbset(a); s64 result; a <<= shift; if (shift < DRM_FIXED_POINT) b >>= (DRM_FIXED_POINT - shift); result = div64_s64(a, b); if (shift > DRM_FIXED_POINT) return result >> (shift - DRM_FIXED_POINT); return result; } static inline s64 drm_fixp_from_fraction(s64 a, s64 b) { s64 res; bool a_neg = a < 0; bool b_neg = b < 0; u64 a_abs = a_neg ? -a : a; u64 b_abs = b_neg ? -b : b; u64 rem; /* determine integer part */ u64 res_abs = div64_u64_rem(a_abs, b_abs, &rem); /* determine fractional part */ { u32 i = DRM_FIXED_POINT; do { rem <<= 1; res_abs <<= 1; if (rem >= b_abs) { res_abs |= 1; rem -= b_abs; } } while (--i != 0); } /* round up LSB */ { u64 summand = (rem << 1) >= b_abs; res_abs += summand; } res = (s64) res_abs; if (a_neg ^ b_neg) res = -res; return res; } static inline s64 drm_fixp_exp(s64 x) { s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000); s64 sum = DRM_FIXED_ONE, term, y = x; u64 count = 1; if (x < 0) y = -1 * x; term = y; while (term >= tolerance) { sum = sum + term; count = count + 1; term = drm_fixp_mul(term, div64_s64(y, count)); } if (x < 0) sum = drm_fixp_div(DRM_FIXED_ONE, sum); return sum; } #endif tree/?id=e47483bca2cc59a4593b37a270b16ee42b1d9f08'>4bc66bd4f2f87a30d231068468d29900685fb45f /fs parent5ce9bfef1d27944c119a397a9d827bef795487ce (diff)
mm, page_alloc: fix premature OOM when racing with cpuset mems update
Ganapatrao Kulkarni reported that the LTP test cpuset01 in stress mode triggers OOM killer in few seconds, despite lots of free memory. The test attempts to repeatedly fault in memory in one process in a cpuset, while changing allowed nodes of the cpuset between 0 and 1 in another process. The problem comes from insufficient protection against cpuset changes, which can cause get_page_from_freelist() to consider all zones as non-eligible due to nodemask and/or current->mems_allowed. This was masked in the past by sufficient retries, but since commit 682a3385e773 ("mm, page_alloc: inline the fast path of the zonelist iterator") we fix the preferred_zoneref once, and don't iterate over the whole zonelist in further attempts, thus the only eligible zones might be placed in the zonelist before our starting point and we always miss them. A previous patch fixed this problem for current->mems_allowed. However, cpuset changes also update the task's mempolicy nodemask. The fix has two parts. We have to repeat the preferred_zoneref search when we detect cpuset update by way of seqcount, and we have to check the seqcount before considering OOM. [akpm@linux-foundation.org: fix typo in comment] Link: http://lkml.kernel.org/r/20170120103843.24587-5-vbabka@suse.cz Fixes: c33d6c06f60f ("mm, page_alloc: avoid looking up the first zone in a zonelist twice") Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Ganapatrao Kulkarni <gpkulkarni@gmail.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Michal Hocko <mhocko@suse.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')