^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) * Lockless hierarchical page accounting & limiting
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) * Copyright (C) 2014 Red Hat, Inc., Johannes Weiner
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) #include <linux/page_counter.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) #include <linux/atomic.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) #include <linux/kernel.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) #include <linux/string.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) #include <linux/sched.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) #include <linux/bug.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) #include <asm/page.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) static void propagate_protected_usage(struct page_counter *c,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) unsigned long usage)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) unsigned long protected, old_protected;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) unsigned long low, min;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) long delta;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) if (!c->parent)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) min = READ_ONCE(c->min);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) if (min || atomic_long_read(&c->min_usage)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) protected = min(usage, min);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) old_protected = atomic_long_xchg(&c->min_usage, protected);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) delta = protected - old_protected;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) if (delta)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) atomic_long_add(delta, &c->parent->children_min_usage);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) low = READ_ONCE(c->low);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) if (low || atomic_long_read(&c->low_usage)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) protected = min(usage, low);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) old_protected = atomic_long_xchg(&c->low_usage, protected);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) delta = protected - old_protected;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) if (delta)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) atomic_long_add(delta, &c->parent->children_low_usage);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) * page_counter_cancel - take pages out of the local counter
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) * @counter: counter
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) * @nr_pages: number of pages to cancel
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) long new;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) new = atomic_long_sub_return(nr_pages, &counter->usage);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) propagate_protected_usage(counter, new);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) /* More uncharges than charges? */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) WARN_ON_ONCE(new < 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) * page_counter_charge - hierarchically charge pages
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) * @counter: counter
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) * @nr_pages: number of pages to charge
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) * NOTE: This does not consider any configured counter limits.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) void page_counter_charge(struct page_counter *counter, unsigned long nr_pages)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) struct page_counter *c;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) for (c = counter; c; c = c->parent) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) long new;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) new = atomic_long_add_return(nr_pages, &c->usage);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) propagate_protected_usage(c, new);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) * This is indeed racy, but we can live with some
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) * inaccuracy in the watermark.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) if (new > READ_ONCE(c->watermark))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) WRITE_ONCE(c->watermark, new);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) * page_counter_try_charge - try to hierarchically charge pages
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) * @counter: counter
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) * @nr_pages: number of pages to charge
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) * @fail: points first counter to hit its limit, if any
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) * Returns %true on success, or %false and @fail if the counter or one
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) * of its ancestors has hit its configured limit.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) bool page_counter_try_charge(struct page_counter *counter,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) unsigned long nr_pages,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) struct page_counter **fail)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) struct page_counter *c;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) for (c = counter; c; c = c->parent) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) long new;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) * Charge speculatively to avoid an expensive CAS. If
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) * a bigger charge fails, it might falsely lock out a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) * racing smaller charge and send it into reclaim
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) * early, but the error is limited to the difference
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) * between the two sizes, which is less than 2M/4M in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) * case of a THP locking out a regular page charge.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) * The atomic_long_add_return() implies a full memory
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) * barrier between incrementing the count and reading
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) * the limit. When racing with page_counter_set_max(),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) * we either see the new limit or the setter sees the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) * counter has changed and retries.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) new = atomic_long_add_return(nr_pages, &c->usage);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) if (new > c->max) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) atomic_long_sub(nr_pages, &c->usage);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) propagate_protected_usage(c, new);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) * This is racy, but we can live with some
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) * inaccuracy in the failcnt which is only used
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) * to report stats.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) data_race(c->failcnt++);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) *fail = c;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) goto failed;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) propagate_protected_usage(c, new);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) * Just like with failcnt, we can live with some
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) * inaccuracy in the watermark.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) if (new > READ_ONCE(c->watermark))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) WRITE_ONCE(c->watermark, new);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) failed:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) for (c = counter; c != *fail; c = c->parent)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) page_counter_cancel(c, nr_pages);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) * page_counter_uncharge - hierarchically uncharge pages
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) * @counter: counter
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) * @nr_pages: number of pages to uncharge
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) struct page_counter *c;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) for (c = counter; c; c = c->parent)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) page_counter_cancel(c, nr_pages);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) * page_counter_set_max - set the maximum number of pages allowed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) * @counter: counter
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) * @nr_pages: limit to set
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) * Returns 0 on success, -EBUSY if the current number of pages on the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) * counter already exceeds the specified limit.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) * The caller must serialize invocations on the same counter.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) for (;;) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) unsigned long old;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) long usage;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) * Update the limit while making sure that it's not
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) * below the concurrently-changing counter value.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) * The xchg implies two full memory barriers before
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) * and after, so the read-swap-read is ordered and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) * ensures coherency with page_counter_try_charge():
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) * that function modifies the count before checking
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) * the limit, so if it sees the old limit, we see the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) * modified counter and retry.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) usage = atomic_long_read(&counter->usage);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) if (usage > nr_pages)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) return -EBUSY;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) old = xchg(&counter->max, nr_pages);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) if (atomic_long_read(&counter->usage) <= usage)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) counter->max = old;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) cond_resched();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) * page_counter_set_min - set the amount of protected memory
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) * @counter: counter
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) * @nr_pages: value to set
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) * The caller must serialize invocations on the same counter.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) void page_counter_set_min(struct page_counter *counter, unsigned long nr_pages)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) struct page_counter *c;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) WRITE_ONCE(counter->min, nr_pages);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) for (c = counter; c; c = c->parent)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) propagate_protected_usage(c, atomic_long_read(&c->usage));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) * page_counter_set_low - set the amount of protected memory
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) * @counter: counter
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221) * @nr_pages: value to set
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) * The caller must serialize invocations on the same counter.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) struct page_counter *c;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) WRITE_ONCE(counter->low, nr_pages);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) for (c = counter; c; c = c->parent)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) propagate_protected_usage(c, atomic_long_read(&c->usage));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) * page_counter_memparse - memparse() for page counter limits
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) * @buf: string to parse
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) * @max: string meaning maximum possible value
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) * @nr_pages: returns the result in number of pages
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) * Returns -EINVAL, or 0 and @nr_pages on success. @nr_pages will be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) * limited to %PAGE_COUNTER_MAX.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) int page_counter_memparse(const char *buf, const char *max,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) unsigned long *nr_pages)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) char *end;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) u64 bytes;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) if (!strcmp(buf, max)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251) *nr_pages = PAGE_COUNTER_MAX;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255) bytes = memparse(buf, &end);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256) if (*end != '\0')
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257) return -EINVAL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259) *nr_pages = min(bytes / PAGE_SIZE, (u64)PAGE_COUNTER_MAX);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) }
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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