On Sat, Jun 22, 2013 at 12:07 AM, Davidlohr Bueso <davidlohr.bueso@xxxxxx> wrote: > On Fri, 2013-06-21 at 21:34 +0200, Sedat Dilek wrote: >> On Fri, Jun 21, 2013 at 10:17 AM, Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote: >> > Hi all, >> > >> > Happy solstice! >> > >> > Changes since 20130620: >> > >> > Dropped tree: mailbox (really bad merge conflicts with the arm-soc tree) >> > >> > The net-next tree gained a conflict against the net tree. >> > >> > The leds tree still had its build failure, so I used the version from >> > next-20130607. >> > >> > The arm-soc tree gained conflicts against the tip, net-next, mfd and >> > mailbox trees. >> > >> > The staging tree still had its build failure for which I disabled some >> > code. >> > >> > The akpm tree lost a few patches that turned up elsewhere and gained >> > conflicts against the ftrace and arm-soc trees. >> > >> > ---------------------------------------------------------------------------- >> > >> >> [ CC IPC folks ] >> >> Building via 'make deb-pkg' with fakeroot fails here like this: >> >> make: *** [deb-pkg] Terminated >> /usr/bin/fakeroot: line 181: 2386 Terminated >> FAKEROOTKEY=$FAKEROOTKEY LD_LIBRARY_PATH="$PATHS" LD_PRELOAD="$LIB" >> "$@" >> semop(1): encountered an error: Identifier removed >> semop(2): encountered an error: Invalid argument >> semop(1): encountered an error: Identifier removed >> semop(1): encountered an error: Identifier removed >> semop(1): encountered an error: Invalid argument >> semop(1): encountered an error: Invalid argument >> semop(1): encountered an error: Invalid argument >> > > Hmmm those really shouldn't be related to the message queue changes. Are > you sure you got the right bisect? > > Manfred has a few ipc/sem.c patches in linux-next, starting at commit > c50df1b4 (ipc/sem.c: cacheline align the semaphore structures), does > reverting any of those instead of "ipc,msg: shorten critical region in > msgrcv" help at all? Also, anything reported in dmesg? > First, I reverted all IPC patches from akpm-tree within -next. Then, I isolated the culprit by git-bisecting. As I checked my logs I did not see anything helpful. >> The issue is present since next-20130606! >> >> LAST KNOWN GOOD: next-20130605 >> FIRST KNOWN BAD: next-20130606 >> >> KNOWN GOOD: next-20130604 >> KNOWN BAD: next-20130607 || next-20130619 || next-20130620 || next-20130621 >> >> git-bisect says CULPRIT commit is... >> >> "ipc,msg: shorten critical region in msgrcv" > > This I get. I went through the code again and it looks correct and > functionally equivalent to the old msgrcv. > Hmm, I guess a rcu_read_unlock() is missing? [ next-20130605 ] ... /* Lockless receive, part 3: * Acquire the queue spinlock. */ ipc_lock_by_ptr(&msq->q_perm); rcu_read_unlock(); ... [ next-20130621 ] ... /* Lockless receive, part 3: * Acquire the queue spinlock. */ ipc_lock_object(&msq->q_perm); ... Whereas ipc_lock_by_ptr() is equivalent to: rcu_read_lock(); ipc_lock_object(); >> >> NOTE: msg_lock_(check_) routines have to be restored (one more revert needed)! > > This I don't get. Restoring msg_lock_[check] is already equivalent to > reverting "ipc,msg: shorten critical region in msgrcv" and several other > of the msq patches. What other patch needs reverted? > No, you have to revert both patches as the other removed msg_lock_[check] afterwards. > Anyway, I'll see if I can reproduce the issue, maybe I'm missing > something. > Yupp, I try with adding rcu_read_unlock()... and report. - Sedat - > Thanks, > Davidlohr > >> >> Reverting both (below) commits makes fakeroot build via 'make dep-pkg" again. >> >> I have tested the revert-patches with next-20130606 and next-20130621 >> (see file-attachments). >> >> My build-script is attached! >> >> Can someone of the IPC folks look at that? >> Thanks! >> >> - Sedat - >> >> >> P.S.: Commit-IDs listed below. >> >> [ next-20130606 ] >> >> http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/log/?id=next-20130606 >> >> "ipc: remove unused functions" >> http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=8793fdfb0d0a6ed5916767e29a15d3eb56e04e79 >> >> "ipc,msg: shorten critical region in msgrcv" >> http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=c0ff93322847a54f74a5450032c4df64c17fdaed >> >> [ next-20130621 ] >> >> http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/log/?id=next-20130621 >> >> "ipc: remove unused functions" >> http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=941ce57c81dcceadf55265616ee1e8bef18b0ad3 >> >> "ipc,msg: shorten critical region in msgrcv" >> http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=62190df4081ee8504e3611d45edb40450cb408ac > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>